Years ago I had Kappa 7’s and was using a Yamaha M85 amp and was satisfied for years. Then I bought a McIntosh MC352 that was a dealer demo who also had sold the Infinity line and Yamaha in a previous store. He told me that I would be satisfied and surprised at the difference in sound.
Well he was right, I had planned to buy new speakers within a year and ended up keeping the Kappas another 5 years. The McIntosh amp with autoformers took on the characteristic varying impedance load of the Kappa and just smoothed them out. I am pretty sure you will have trouble finding a used McIntosh amp in the price range you indicated but it would be well worth your time and extra bucks to wait till you can find one that fits your pocketbook.
I miss the emit tweeter and the deep controlled bass of the Kappas. good luck! Those are great speakers.