The first thing I'd look for would be any old 1970s/1980s receivers being sold locally at low prices. They should power any SRD-7 adequately. The question is what receiver to pick...
In my case, I use an old Onkyo TX-SV515PRO receiver that was just sitting boxed up in a closet otherwise. It would be better if I could have used that Sansui 8080DB that was also sitting boxed up in a closet, but that's not an option for now. (Neither are those expensive dedicated Stax amps...)
My setup's a bit different (Normal bias SR-Lambda + SRD-7/SB, and back when I had the SR-202, it came with an SRM-212), but it's similar enough.