Probably, but I would suggest you read the Schedule C regs closely. There are conditions that may make it fully deductible, partly deductible or not deductible at all. I am working on the notion that you were paid enough to perform the shop in bonuses or whatever to make the shop a viable proposition.
When I drive 150 miles round trip to visit family and do a gas station shop in their city at list price, my gut tells me that I could not comfortably defend claiming a deduction for the 150 miles for a $15 shop. If, on the other hand, I drove those 150 miles, stayed over with family and the following day performed heavily bonused shops and picked up other shops that would have made the drive worthwhile, I would claim the mileage.