Don't waste your money on that. There are better AR's made for close to what your going to spend compared to that DPMS and that upper is more toy than it is an actually a good basic AR upper setup.
That fake silencer/handguard setup serves no purpose but look and you'll have no frontsight without putting more into. That's more than likely his stupid purchase that he's trying to pawn off on you.
I recommend you take that money and get yourself a good complete lower of which there are nice deals all the time in the E&E or just buy actual good shtf AR setup from someone selling theirs here in the E&E too.
If you want to buy new than there are lots of good deals on lowers and uppers to be had, but don't waste the money on rifles right now that are more toys than tools compared to others when you're just starting out in the AR game. You'll be much better off starting with a nice mid length or M4 16 inch barreled AR flat top upper with a good railed gas block to be able to refine later what you want in sights and optics and if you want to put a little more into it you'll get more out of it. That way for you there is less to mess with and less to mess up till you know more about the rifles.
Example:
Bravo uppersCWSRainierArmsRainier lowersA Bushmaster sale from AimSurplus,
E&E adYou just find a local FFL to have it transfer to like buying a complete lower. You won't pay tax and you just pay the transfer fee through your FFL.
For separate complete uppers you have them delivered straight to your door as there considered nothing but another part and you don't need to transfer them. The lower is the registered part.