Yes, you can find a doctor based on cost but I do not think it is the best approach. Cost for breast augmentation varies doctor to doctor and region to region but the average cost in your area should be similar among surgeons. That reflects a need to stay competitive but also factors in the minimum costs the doctor incurs to actually be able to do the surgery - implant cost, anesthesia cost, cost to use surgery facility, etc. Cost of living in your area is also a factor. In general breast augmentation is more expensive in places it is more expensive to live.
One thought is to have the surgery elsewhere in the U.S., like someplace you have family living where you can stay, recover, and help you if needed. The main problem with this, however, is difficulty following up from far away if you have problems or need to see your surgeon.
Moving away from cost, I recommend that you also focus on qualification, board-certification, and experience of the surgeon. If you get a bad result by picking a surgeon that offers bargain basement pricing, you may end up paying a lot more in the long run to have it fixed or have your malpositioned implants removed.
See at least three plastic surgeons. Get prices. See who you like and go forward from there.