My husband is a dentist and uses Zoom with excellent results. He says that you do need to be careful what you eat afterwards (wine, coffee etc.) and that it is entirely normal to experience "zingers" or twinges of pain (nothing horrible) for 24 hours afterwards. Your dentist should also give you bleaching trays to use only to touch up when necessary- don't be shy, use them when you feel you need to brighten up.
As for the cost, it all depends on where you live. My hubby charges $350 but we live in Michigan where the cost of living is lower than in other parts of the country. Hope this helps! Feel free to PM me if you have any questions, and I will have my hubby answer it! Good luck!