Haha you'd definitely be better off just buying a full course or making your own stuff. Most barns use their jumps until they're either broken, decaying, or both, so the chances of finding someone willing to give you their usable stuff is probably around 1 to a jillion. (I'm sure everyone knows of or has been to a barn where the owner just can't let go of their dilapidated course) Especially if your barn if going to have shows that charge more than 10 dollars a class, you guys probably want to have some decent looking jumps. If 3000 bucks is completely out of the question for a course, (just google "horse jumps" and look at the top 5 hits) then Lowes/Home Depo would be your best bet. Lumber and paint are cheap, so all you need is someone with some screw driver skills to make the standards. My barn made it's own standards and decorated our PVC pipes with spray paint, (as pictured in my icon) and we've made a coop one time but had to scrap it eventually because the wood wasn't strong enough to hold up against the horses chipping it. Any art store carries the flowers too, so those are easy to find, and I think country supply/ebay has cheap jump cups.
You can buy lattice for really cheap and it makes your homemade jumps look proffesional. Make your own using fake flowers from Walmart. Stick them into stirofoam and use rocks from the pastures to hold the flower pots down.
If you get a block of wood, you can simply drill holes in the top and buy fake flowers to stick in the holes. Voila. Flower box. :) Also, it will definitely be cheaper to make your own jumps, as others have said. Wood and paint is the way to go, or you can get PVC pipe, like someone else mentioned.