That's a fancy upper. I couldn't spend that kinda money on one lol. I bought a PSA 16" 1 in 7 twist carbine length for 300 and it stung a little, but I'm over it now lol. Grats on the buy.
CTUAgent - one thing to keep in mind is that the $300 PSA upper likely did not include a bolt/carrier group or charging handle, both of which were included in the OP's upper for the price (along with the free-float rail). Add those options to a PSA upper and the price rapidly goes up.