Read the thread "the most important piece in a stereo system" as this will guide you on how to allocate your budget.
You have two general categories to pick from: dynamic cone driver system or planar system. Both have pros and cons, but your room 20'x15' will accomodate either.
Having said that, I like the recommendation for the Rogue integrated at 1400 used, if you can get one. Run it in triode and match it up with a pair of efficient Coincident or Silverline speakers. Use a Rega Planet 2000 cdp (700 used) and Coincident IC, power cable and spkr. cables (500 used).
For a planar system, consider a Magnepan 1.6qr (1200 used), Plinius 8100 integrated (1200 used) and the above cdp and cables.