That is why you travel by foot/public transit from a good distance away, covered up, and without a cell. Arrive at the back of the lot where the day workers congregate and make the offer for more cash than what the purchase costs to an individual to go inside and purchase some items. Ideally, you'll want to spread these purchases across multiple jurisdictions, days (or more), wearing different coverings, and mixing in nondescript items with the purchases. If the first individual refuses, leave and make an attempt elsewhere, don't make this memorable.