These were prices even when Clinton was in office!
I don't ever remember seeing a complete AR for under $500... $500 and over, yes

Vendors at every gunshow
SKS $50
AK's $150- Mags $2
M1 Carbines $99
Mosin Nagant $25
M1 Garand $150
Sten Guns $50
Europen Mausers $50