Machining, A hobby with a payoff if your good...
All the basic machines required to make a basic Bolt rifle: $3500 (No top-of-line stuff(a good lathe though), just a lathe, mill, grinder, rotary tool, planer).
Bits to Bore, Rifle, and ONE chamber reamer: $500
Headspace guages: $75
Bit's to actually cut all the other parts: $300+++
Die/tap/drill-bit's for one gun: $200+
One 72" 440C high-carbon Stainless steel rod, 1.5" dia: $188 (aluminum and plain steel are cheap, thats for the rest of the gun)
Hardening of steel (not sure, didnt shop around yet, probably in the $100-$200 range for just a barrel )
Add to this all the other stock material, plus furniture, plus probably a bunch of other stuff I forgot.
Ten again, a toy like this could sell, and if you know what your doing, and make it look cool, it'll pay back whatever it cost you.
Bah, who am I kidding, I wouldn't sell any guns I make [:P]