Chip racks, umbrellas, geegaws
Children of the Lord (and all others), chip racks are free if you can drive to the nearest snack wholesaler. Call them first, talk to the manager, tell them you are a mobile vendor and want to come down and look at everything. On your way out, nail a few clip racks. Simple as that little kittens.
Umbrellas and signage? Vienna sets their vendors up if you go exclusive. I don't wish to do this and I think their colors are ugly.
Drinks? Call up your local Pepsi or Coke distributor directly. If they like your location, they might just do you a deal you won't believe if you do an exclusive. More signage, more stuff.
What else? Don't be afraid of minimum orders of $250 for non-perishables. Remember that whoever you are talking to on the phone gets paid to load you up with goodies.