I don't think the materials are all that expensive, not compared even to a cheap welded say Surly level frame. Let alone a custom. But you won't save a dime getting into frame building as a hobby. Most expensive tools of any hobby out there, for what you get. We need someone like the President of Grizzly tools to take up framebuilding and get us some BB taps, etc... for 30 bucks.

You can make a decent whole frame out of 4130. I get mine from aircraft spruce. The chromo generic tubes are pretty cheap in butted, Nova sells them and has lots of options that aren't in the catalog. The only part that hurts is that the tubing sets they use for "quality" Asian butted bikes, are about 10 bucks a set according to someone who was posting here, and had far east manufacturing experience. Might sound preposterous, but I have that kind of experience in the knife area, and knives that sell here for 80 bucks and up are bought for about 4 bucks. My local dollar store sells some kind of combo lockback for a buck. Stainless blade, anodized scales, looks nice at the least. So we are getting heavily reamed. Keep in mind these products are heat treated (dollar store not so sure...), which is two steps up from what our tubes are.