This project took Hamilton and I about four hours to build (see the plans here: http://ana-white.com/2013/11/plans/changeable-play-stand-lemonade-market-post-office-theater-bakery-and-more). The materials totaled about $60, and that's using new, quality lumber. You could probably find most of it for free if you were willing to troll Craigslist for a few days! I also sewed the banners myself (solid broadcloth at Joann's goes on sale for $1.99/yard, you'll need only 1/4 yard of each color). The berry baskets were my own addition to the original plans--I really like the look of having all of the food items organized into baskets instead of laying haphazardly about. You can buy berry baskets on Amazon, Etsy, or get them for free at your local farmers market!
I used a black foam posterboard (cut with an exacto-knife) and chipboard letters from Hobby Lobby for the market sign, and hot glued the little chalkboard signs (also from Hobby Lobby) underneath the baskets as an added touch. All of the felt food is homemade, of course! I will be posting free printable patterns for them soon :).