Since ideally, you'd want to have a set of speakers that compliments each other sonically, it's difficult to pick out the best center or surrounds for a future system without knowing what main speakers you'll be going with when you upgrade your current mains. A couple different routes you could take, you can either save up more $$$ and get the new mains first (as already mentioned in an above post), or just audition and pick out the mains you'd like to have when you do upgrade your mains, and from there you could pick surrounds and a center that match those mains and go ahead and get one or both of those if you'd like to take a smaller step now towards your future system.
With that said, at the price point you mentioned, Paradigm makes some nice speakers that I've always found to be accurate and versatile. I bought a Paradigm speaker system for my father 3 years ago. The system was not very expensive, but sounded very good, and I felt it didn't color the source material. Again the word accurate comes to mind. This particular system was from Paradigm's Performance series, which is a quality on a budget line, but they have several different lines of speakers at different prices. I have found many of their $200-400 dollar speakers to have some of the great qualities of their more expensive speakers at a very reasonable price point. They are definately worth a listen if there is a dealer in your area.
Axioms mentioned earlier in this post, you probably can't go wrong with Axioms based on all the positives raves about Axioms found throughout this forum. People here seem to love them. I'd love to hear a set myself, but never have, so you have to rely on other's knowledge there. On that note, anybody live near Louisville, Kentucky with a set of Axioms? I'd like to come over and listen! HA! Seriously, I'd like to listem to some Axioms and see what the buzz is about! I probably should say "raves" instead of "buzz" when talking about speakers.
Putting the system together in pieces is a great idea; I've never bought an entire system all @ once. Get some nice components for the system, save up and add on the next component... All this talk of speaker systems makes me want to go put together a new secondary HT system for my bedroom or basement!
Have fun, and let us know what you end up going with and how it sounds.
Brad
