For your budget, I think the Andrew Jones' Pioneer speakers are one of the best options. Used is another good option, and speakers generally hold up well over time if they aren't abused too much.
I would maybe start with 3.1 and add in surrounds later. You could get a pair of the FS52 towers, the C22 center, and a Dayton SUB1200 for $400, and then down the road add a pair of BS22s for surrounds. I would lean towards the Denon AVR-1913, the 1712 is 7.1 also but does not have networking.
Samsung PN60F5300 | Denon DBP-1611 | Roku 3
Denon AVR-1713 | EMP E55Ti | EMP E56Ci | EMP E5Bi | BIC F-12
Topping TP23 | NHT SuperZero 2.0 | Velodyne DEQ-8R