At what price do amps start to sound

I can wax rather eloquently about speakers, but amplifiers are something that I know very little about. Actually it's probably a lot less than a little. So please tell me, at what price (generally speaking - of course there are alway exceptions) does one start finding amplifiers that offer decent sound and begin to hint at what the big boys can do? Now as a camparison, I can say that for around $700 new, you can begin finding audiophile-like mini-monitors (if you do your homework) that image well and convey a wonderful sense of space and excellent timbral qualities on instruments and voice. And if you're willing to spend somewheres between 3-4K new, you can have yourself a very satisfying listening experience with great sound quality. Of course if you can spend 10, 20, 50, or 100K you can get the best of the best.

So what is a comparable price point with power amplifiers? At what price (again generally speaking - and if I do my homework) can I begin to hear good imaging, depth and timbre?