It is a common misunderstanding that the cost of LASIK depends on the prescription. While some low cost centers might connect the price of LASIK eye surgery to your prescription, the most common reason for this is that they are using an older laser, older technology, and outdated laser vision correction treatment methods for this low cost option.
They do not provide custom wavefront all-laser LASIK using the newest upgraded laser technology for these low price options. Most often they try to bait-and-switch patients by dangling low prices (such as $600 per eye) and then convince patients that due to astigmatism, moderate myopia, and higher order aberrations they will need to upgrade the costs or they might sacrifice safety. This scare tactic seems a bit dishonest in my mind.
LASIK is not an inexpensive procedure. Generally you should expect at least $2000 per eye if not more. The best surgeons and the best technology generally cost around $2500 per eye or more. If your price is a fraction of this (as are sometimes advertised in various markets), then there is a chance that your surgeon is cutting corners and providing a less safe and less accurate treatment.