Look to the used market for some good amps in that price range, Anthem, Rotel, NAD, to name a few. You can also check out Outlaw Audio, they offer some nice amps and since you own M80s you could try Emotiva but ther have been a few with M80s having problems with Emotiva's amps and M80s, but there are a number that are using them with no problems, so YMMV.

M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70