Like everything else you have to shop. Actual Colt M-16's sell for 5000.00 to over 8000.00 depending on model. Decide if you really need an A2. Could you deal with a 5000.00 A1 and put an A2 upper on it. Registered Recievers (COLT SP1) sell for 4000.00 to 5500.00. Then there are the non-Colt guns. I recently bought a SGW M-16 (actual factory full-auto) for 4800.00. Go to www.subguns.com,
then go to Message Boards, NFA for sale. Check the prices, remember posted prices are not always what they sell for. There have been Colt M-16 A2's on the boards for months at 10,000.00. You don't see the 8500.00 ones posted twice. Check also www.ar15.com.