Steel prices are getting nuts. We just paid almost $ 200 for a stick of 1 3/4 inch round tubing to use for crossmembers, it was slightly over $ 100 a few months ago. I think we will see the prebuilt frame prices starting to climb soon, they have to be getting squeezed too.
We have always built our own just because we like to use certain sized tubing. We like 2 x 3 and 2 x 4 with a wall thickness of 3/16. The edges round over nicer than 1.5, it is stronger, and the 3/16 wall lets us drill and tap for non structural items to be mounted (brake lines, cables, wires, etc)
I have been approached from time to time to build someone a frame and have had to turn it down each time. First of all, it is very labor intensive to do it right, and the material costs alone run $ 300 to $ 500 by the time you figure in crossmembers, perches, and rails. There is no way you could charge a person enough to make a buck and still be competitive.
But if a person is a good welder and takes their time, you can get a nice frame that is custom made to your specs. It is the only way to get one that sits exactly how you want it too, otherwise you just take what is on the rack and go with that.........which is fine in lots of cases.
Don