I don't see anything on Audiogon right now that would fit the bill, from my quick look.
You could probably get away with the Emotiva LPA-1 (125x5 plus 50x2). The RS6 is 6 ohm and reasonably sensitive so the LPA-1 would have no problem driving it. And for $499, you're stealing it.

The only question would be your listening habits and how hard you want to drive it.
The Emotiva MPS-2 would also seem to be a safe bet and you will never have to second guess whether you have enough amp. Although I haven't owned one myself (yet), I defer to the other users here that are happy with them. It's hard to beat 7 channels by 200w in a single chassis for $1,699 new with warranty. I know it takes up most of the current budget, but you can run it with your receiver for now and choose a pre/pro sometime this summer.
I also understand that Outlaw is a good choice for a 7 channel amp.
Or you could look at a Rotel 1075/1080 combo or and Anthem PVA5/MCA2 combo, but these come with some compromises, like two separate chassis, a lower power 5 channel amp and probably more expensive.