Hi Charles, 1/2" steel would be overkill for what you need and as you have found out, very costly.
If you give us a sketch or some pictures of what you are trying to do, then we may be able to offer some more useful suggestions. I assume you were thinking steel as there is an issue with height.
Personally I would be looking at a lumber issue, but without any idea of what we are working with, it is impossible to say at this point.