Ok, a little late to this party, but I thought I'd chime in to recommend a Cambridge Audio integrated amp. I've got a A500 int amp I picked up for about your budget level to use in my home office system. I like it a lot and would definitely recommend it. I think the newer Azur line is a bit more expensive than what you want to spend, but if you look for an A300 or A500 used, you should be able to get it at or below your budget.
I also like the preamp + B&K or Acurus idea (I used to use that myself for my main system). But by the time you pick up a preamp, even going used you'll be looking at double your budget or more.