8x10 is going to be way too small for a full sized horse. My girls are in 12x12 and I couldn't imagine them being in anything smaller, YIKES!
I love the look of the pre-made stalls but they are sooo expensive!
Now that you mention it 8x10 is kinda small. I need to take a tape measure out there and see what room I got to work with. Probably more than I think I do. I looked at some pre-made stalls last night online. Just to have a front and two side was going to be bout 2 grand. I looked and it doesn't seem to difficult to make them. Going to price material tomorrow. Local welding shop is having an open house so maybe there will be some good deals.