I format all my own e-book files (and hand-code the HTML for perfect results).
If you want your formatting to be perfect, I recommend doing the same. It's a bit of a pain to learn, but you will get the hang of it in a day or two. After that, it's relatively painless.
Guido Henkel has an excellent, free step-by-step guide to doing it yourself (
here).
If you want to hire someone, the pros charge about $200, but they also have waiting lists.
Guido Henkel will do it for $100 for a basic book (with no links or images), going up to about $150 for books with those extras.
I do my own, but if you want to pay for it, I highly recommend him.