Windham is a very good option. Once in a blue moon, their HBAR rifle can be found for under $700. He'll have money left over for mags and ammo
But if he wants to spend a $1000, a Colt 6920 HBPW is an excellent MD option that should hold decent resale value.
Colt or FN
This right here.
Sig M400 Tread or POF P-15 constable. Colt or FN if you want a basic rifle.
The same thing I buy now every time I have an extra thousand, Colt (although I snuck in an FN at the top because....why not?):