You definitely need some sort of weight. Hopefully you won't have a problem but if the wind picks up you will be glad you are prepared. I have done dozens of outdoor craft fairs and the wind can be your worst enemy. Your stuff might not be breakable, but your neighbors might be, and it does not take much of a breeze to turn a canopy into a sail.
One way to make cheap weights that do not look too bad is to use the big pvc pipe. You can get it in various diameters. I think the 4 inch works pretty well. Cut it to whatever length you think you can handle. 18 inches or there about works pretty well. Then glue caps that fit to one end. Then fill with sand. For the other end drill a hole and install an eye bolt with washer and nut on the inside. My husband recommended that that end is screwed on, but if that is not possible they do make a good permanent glue. You need to have at least one, preferably two for each corner. I hang them with good bungie hooks, but a rope with hooks would probably work better. After they are hung you can bungie them to the legs.
Another thing we have done in emergency situations, when we forgot the weights or needed more is to use gallons of water. A gallon of water weighs about 8 pounds so you would need several per leg, but they do work. Some people even use empty gallons then fill them on site, if you have water there.
I would think for a show where you are selling your quilts that using your best quilts for your walls would give the whole booth a great look. If heat is a factor, maybe just tops so the air can move would be good. I've seen beautiful booths full of quilts that are simple and not fussy. Just the quilts on the three inner walls and then more stacked on tables across the front. Sometimes simple is better. You want your product to shine.
Oh another idea, if you are on a corner or have a outer wall that is exposed, hang a quilt there. Anything that will draw the crowds eye to your booth. Also if you can make some sort of flag that you can stick to the top front of your booth is also good. It makes people that might want to come back, find your place.