This is way down the list, but when you're ready, it might be worth a trip to Costco. For sure you can get high quality folding tables and related stuff for less than you've budgeted. If you ever get to Houston, the Costco Business center might be a gold mine.
Also there are auction houses that specialize in selling materials from defunct restaurants. Once you figure out the menu and licensing details, one thing to keep in mind is spending as little as possible to get durable supplies. Developing a theme to make you memorable doesn't hurt either.
Back in the early 2000's, a woman used to work at Chez Panisse. Her nickname was Betty and she longed to start a bakery business. In the beginning, she baked all night, then sold her wares at a farmer's market. Desperate for easily portable, sturdy tables to display her wares on the cheap, she hit on the idea of using ironing boards. She also wore a blue wig so people would remember her. Eventually, there were a number of blue wigged, ruffled aproned "Bettys" selling baked goods piled high on ironing boards at several Bay Area farmer's markets. Ultimately, the business morphed a bit and she now owns a single restaurant, serving a signature chicken sandwich that was an unexpected hit, buoyed by social media reviews. The restaurant is called "Bakesale Betty".