I'd also like to chime in and tell you that you do not have to get a Padi certification. Any agency will get you a card and allow you to dive. I started out in Padi, and became a Padi instructor, but as the years went on, their course curriculum made some changes that I personally was not happy with... so I crossed over to Naui.
At our shop, we have a lot of padi instructors as well.... but we do Naui classes most all the time. They are a little more challenging, a bit more education as far as the physics and physiology, a little more challenging swim test, more snorkeling exercises, plus you will do a rescue drill that is not the easiest to accomplish, but it was because of these differences that I decided to teach Naui courses.
But as most have said here, I would not look at the price. In fact, some make that confusing as they will give you a price, then you buy over priced gear, or have to pay for books, or pay rental fees when it's time for checkout dives, etc... so make sure if working off price - look at apples and apples.
I also would not look at the acronym on the card. I'd go look at multiple stores and see which one works best for you. Look at their pool. Check out their class room, look at the gear you will use, look at the gear available to purchase, then make an informed decision based on what is the most comfortable for you.
Obviously, I invite you down to visit our shop, but also would tell you to check with others as well.