Killer used integrated for

Go up to $900 and get a used Peachtree Nova 150. I owned it and sold it after a few years. It served me quite well.

Not possible ,

+1 for Exposure if you can find one. Good stuff.

When you say 'killer', if you mean decent 2 channel integrated, then consider the Cambridge Audio Azur 851A. I've seen them used for $500.  Good luck

It would be helpful to know what speakers you will be using in order to make a good recommendation. In my bedroom system I use a Rega Io and Tannoy Mercury speakers. It's a great sounding amplifier that punches way above it's $599 MSRP. However, it requires careful speaker matching as it only puts out 30wpc. Good Luck!