if you want to save some headaches to yourself, just play safe and use relaible companies. You may spend a few bucks more, but you'll save them in the short run. That being said, for that kind of task I wouldn't use anyone but:
http://dickmansdesign.com/ (the best hands down)
http://adultdesign.com/ (close to the best but lately their quality is slightly lower than usual)
http://fdsign.com/ (the CSS wizard himself)
in that order. Price goes down in that order too, but all 3 of them are safe bets. If you're looking just for programming and/or just implementation you'd better go with k0nr4d or
http://mechbunny.com/ or w0j rather than a design company
and that's about it, you'll thank me later
