For the purposes of the County Purchasing Act, in a county where each commissioner is in charge of the roads in his precinct, can each commissioner purchase material from the same supplier if the cost does not violate the County Purchasing Act and their intent is not to go around the law.

Based on your description of the facts, presuming the purchases will not be $25,000 or more (or component purchases aggregating $25,000 or more), the purchases won't come within the purview of mandatory competitive bidding under section 262.023 or section 271.024. One caveat is appropriate, however. If your county has a purchasing agent, it is the purchasing agent -- not the individual commissioners serving as road commissioners -- who must make the purchases. See Tex. Loc. Gov't Code sec. 262.011(d). As a practical matter, I tend to be a bit suspicious of "good deals" that evade competitive bidding, and, being the paranoid, suspicious type, I'm inclined to look at the proposed purchases very closely to ensure that they aren't, in fact, component purchases intended to evade the competitive bidding requirements.