Best value represents the overall "best" solution, not just the lowest overall price.  When determining what is a "best value," the following factors may be considered:

FAR, Subpart 8.4--Federal Supply Schedules
§ 8.404 Using schedules.
(a)  General. When agency requirements are to be satisfied through the use of Federal Supply Schedules as set forth in this subpart, the simplified acquisition procedures of Part 13, the small business provisions of Part 19 do not apply, except for the provision at 13.303-2(c)(3).Orders placed pursuant to a Multiple Award Schedule (MAS), using the procedures in this subpart, are considered to be issued pursuant to full and open competition see 6.102(d)(3)). Therefore, when placing orders under Federal Supply Schedules, ordering offices need not seek further competition, synopsize the requirement, make a separate determination of fair and reasonable pricing, or consider small business programs.GSA has already determined the prices of items under schedule contracts to be fair and reasonable.
By placing an order against a schedule using the procedures in this section, the ordering office has concluded that the order represents the best value and results in the lowest overall cost alternative (considering price, special features, administrative costs, etc.) to meet the Government's needs.

(b)  Ordering procedures for optional use schedules--

(1) Orders at or below the micro-purchase threshold. Ordering offices can place orders at or below the micro-purchase threshold with any Federal Supply Schedule contractor.

(2) Orders exceeding the micro-purchase threshold but not exceeding the maximum order threshold. Orders should be placed with the schedule contractor that can provide the supply or service that represents the best value. Before placing an order, ordering offices should consider reasonably available information about the supply or service offered under MAS contracts by using the "GSA Advantage!" on-line shopping service, or by reviewing the catalogs/pricelists of at least three schedule contractors and select the delivery and other options available under the schedule that meet the agency's needs. In selecting the supply or service representing the best value, the ordering office may consider--

(i) Special features of the supply or service that are required in effective program performance and that are not provided by a comparable supply or service;

(ii) Trade-in considerations;

(iii) Probable life of the item selected as compared with that of a comparable item;

(iv) Warranty considerations;

(v) Maintenance availability;

(vi) Past performance; and

(vii) Environmental and energy efficiency considerations.

(3) Orders exceeding the maximum order threshold. Each schedule contract has an established maximum order threshold. This threshold represents the point where it is
advantageous for the ordering office to seek a price reduction. In addition to following the procedures in paragraph (b)(2) of this section and before placing an order that exceeds the maximum order threshold, ordering offices shall--

(i) Review additional schedule contractors' catalogs/pricelists or use the "GSA Advantage!" on-line shopping service;

(ii) Based upon the initial evaluation, generally seek price reductions from the schedule contractor(s) appearing to provide the best value (considering price and other factors); and

(iii) After price reductions have been sought, place the order with the schedule contractor that provides the best value and results in the lowest overall cost alternative (see 8.404(a)). If further price reductions are not offered, an order may still be placed, if the ordering office determines that it is appropriate.

(4) Blanket purchase agreements (BPAs). The establishment of Federal Supply Schedule BPAs is permitted (see 13.303-2(c)(3)) when following the ordering procedures in this subpart. All schedule contracts contain BPA provisions. Ordering offices may use BPAs to establish accounts with contractors to fill recurring requirements. BPAs should address the frequency of ordering and invoicing, discounts, and delivery locations and times.

(5) Price reductions. In addition to the circumstances outlined in paragraph (b)(3) of this section, there may be instances when ordering offices will find it advantageous to request a price reduction. For example, when the ordering office finds a schedule supply or service elsewhere at a lower price or when a BPA is being established to fill recurring requirements, requesting a price reduction could be advantageous. The potential volume of orders under these agreements, regardless of the size of the individual order, may offer the ordering office the opportunity to secure greater discounts. Schedule contractors are not required to pass on to all schedule users a price reduction extended only to an individual agency for a specific order.

(6) Small business. For orders exceeding the micro-purchase threshold, ordering offices should give preference to the items of small business concerns when two or more items at the same delivered price will satisfy the requirement.

(7) Documentation. Orders should be documented, at a minimum, by identifying the contractor the item was purchased from, the item purchased, and the amount paid. If an agency requirement in excess of the micro-purchase threshold is defined so as to require a particular brand name, product, or a feature of a product peculiar to one manufacturer, thereby precluding consideration of a product manufactured by another company, the ordering office shall include an explanation in the file as to why the particular brand name, product, or feature is essential to satisfy the agency's needs.

(c) Ordering procedures for mandatory use schedules.

(1) This paragraph (c) applies only to orders against schedule contracts with mandatory users. When ordering from multiple-award schedules, mandatory users shall also follow the procedures in paragraphs (a) and (b) of this section.

(2) In the case of mandatory schedules, ordering offices shall not solicit bids, proposals, quotations, or otherwise test the market solely for the purpose of seeking alternative sources to Federal Supply Schedules.

(3) Schedules identify executive agencies required to use them as mandatory sources of supply. The single-award schedule shall be used as a primary source and the multiple-award schedule as a secondary source. Mandatory use of schedules is not a requirement if--

(i) The schedule contractor is unable to satisfy the ordering office's urgent delivery requirement;

(ii) The order is below the minimum order thresholds;

(iii) The order is above the maximum order limitation;

(iv) The consignee is located outside the area of geographical coverage stated in the schedule; and

(v) A lower price for an identical item (i.e., same make and model) is available from another source.

(4) Absence of follow-on award. Ordering offices, after any consultation required by the schedule, are not required to forego or postpone their legitimate needs pending the award or renewal of any schedule contract.