The purchasing unit is exempt from the operation of the mandatory provisions of section ten, article three of this chapter when:
(1) The director of purchasing determines that the commodity or service so produced or provided does not meet the reasonable requirements of the purchasing unit;
(2) The committee or central nonprofit agency determines that a nonprofit workshop cannot reasonably provide the commodity or service;
(3) The purchasing director determines, after considering any recommendation of the committee or bids which may have been offered, that the commodity or service is not of a fair market price; or
(4) The purchasing director determines, after consulting with the committee, that the commodity or service is not of like quality to other commodities or services available.
No purchasing unit may evade the intent of this section when required goods or services are reasonably available from nonprofit workshops: Provided, That if a purchasing unit is required or may be required by federal statute or regulations to purchase commodities or services with competitive bidding, or may otherwise be disqualified from federal funding or assistance if it fails to purchase commodities or services with competitive bidding, the purchasing unit shall not be required to purchase commodities or services from nonprofit workshops. Such purchasing units not required to purchase commodities or services from nonprofit workshops include military installations of the National Guard.