I didn't go through Airstage 1 at ATA but, from what I understand, ATA is the only school that has a guaranteed cost for Private, Instrument, and Commercial Multi (i.e. you pay your money and they will give you all the flight time you need to complete the program). There may be some "fine print" associated with this deal so make sure you have someone from ATA fully explain it to you before you sign on the dotted line. As a comparison, most other schools quote you a price based on the MINIMUM hours required by the FAA to obtain the ratings in question. This estimate is just that - a VERY LOW BALL guess. It is by no means a guarantee of any kind! Once you start training you're billed an hourly rate for the airplane and instructor. If it takes you more time than the FAA minimums to complete your training YOU PAY FOR ALL THE EXTRA TIME (I would add about 20% to these estimates). For most schools, rather than paying attention to the overall price quote, I would just check on their hourly airplane/instructor rates. It's going to take you about the same amount of time to get your ratings no matter where you go so the school with the lowest rental rates will result in your lowest cost.
Now a couple things about ATA (keep in mind that I'm talking ONLY about Airstage 2). Their ground schools are very good (particularly the CL-65 Regional Jet sim). They also seem to have the best employment connections out of all the schools I've heard of. On the down side their airplanes are ABSOLUTE GARBAGE. They give them just enough maintenance to keep them in the air - barely. I've been at the school for about 5 months and we've already had 3 engine failures in the Aztecs. There have also been more radio failures, hydraulic failures, and other miscellaneous failures than I can count on all my fingers and toes. My best advice is to go somewhere else - ANYWHERE ELSE - for your private, commercial, multi, and instrument ratings. Come back to ATA for Airstage 2 so you can take advantage of their airline connections (if you're comfortable flying some VERY rough airplanes).
By the way, I have some friends that are going through Pan Am's program in Ft. Pierce. Pan Am's airplanes are just about brand new and are first rate. They also has a CL-65 and my friends who have gone through their ACE program have been very satisfied. You might want to try them for your initial training.
Hope that helps!