I want to do some experimenting for a project that I've gotten involved in and I need a few barrels that don't cost an arm and a leg.

I'm sure that there are tons of used GI barrels out there or even barrels that were taken off guns that were being customized.

Any ideas where I can locate all of these barrels?

the equipment exchange, Sarco (see sgn) and ebay.

Used GI barrels are cut in half before they're surplussed thanks to Klinton. Check the EE for cheap barrels. Cheap uppers show up a lot, you could always grab one of those and throw the receiver back on the EE.

I've got an Oly barrel, cut to 10.5", the threaded portion is definitly not coencentric to the bore, and the upper portion of the sight tower was cut off with hacksaw, still have the part. It is a 1x12 twist, but I really don't think it is actually over 500 rounds through it.  I'll take $50, you can make a 9.5" or shorter using a  pistol gas port/tube location.

I also have a DPMS SS Bull barrel, bought it as a 16", had it cut to 12" and SOCOM Mfg did the thread. Paid $240 for the barrel, add threading. Let go for $150, add shipping.

Should have guessed that was the situation. God knows that military surplus barrels are at the root of all crime in this country.

so how did i buy 2 m16a2 barrels last year that were well used??????

Foreign surplus? Pre-executive order surplus? I dunno, I can't seem to find my magic crystal ball right now.