Prices seem to have leveled out for the last several months.
I have been looking at a possible rifle cal purchase and the 1919A4 really seems like it might be the toy to scratch that itch. They are easily had for less than a conversion these days. Seeing a RLL sell for 12K fills my mind with f***...... RDIAS at 30k is absurd. You could literally have your 02/07 for what, 40 years or so before you break even depending on your interpretation of ITAR and whether or not it is even enforceable.
If you are looking hard at a 16 and really don't want to spend all that cash you may keep your eyes toward Shockwave Technologies and his (soon hopefully) release of a quality and cost effective rifle cal upper for the MAC. Supposedly only the upper receiver, bolt carrier assembly and minor internals will be proprietary. The rest (IIRC) including the BBL, bolt, handguard, gas system, etc. are going to be COTS AR parts.
ETA - You will have to drill your lower for a recoil rod, no big deal.