Neighbor put one up with curved walls for hay storage, and no ends. Maybe it was because they had never done one before, but they put a lot of time into making sure the foundation was right so the holes would line up. Then theirs was wide enough that they had to build it one sheet at a time, rather than assembling a "hoop" on the ground and raising it up and bolting to the rest. I was in one that the farmer had sprayed with insulation and used for a shop, and I also would go for the one with straight walls. Unfortuatly I am of no help to you on prices, but if you search on the net you should at least find a rough price.