Hi
DMB,
Whilst I don't know the pricing, I'd like to throw two links I have at you ... with the implied understanding that (like your bed) you'll spend a lot of time working at your desk and sitting on your office chair during your life, so don't skimp on it.
I can't stress this enough - ergonomics (or Human Factors for the US folks) matters!
These will probably be pricey (esp the Aeron ... unless you find it at a blow out sale somewhere) but they'll pay themselves off in terms of quality (they should last a long time) and being designed specifically with your body in mind (they should not give you any grief posture wise).
Herman Miller - Aeron chair
and this other website:
ergo4me - BodyBilt chairs
Nor spamming for sales - I dont' work for these companies ... just letting you know of what I had in my Human Factors folder of bookmarks.