As others have said, the key to a good mask is fit. Some people have faces that will work with any mask. My most recent student, in contrast, has a very narrow face, and after a very long fitting session determined that only two masks out of the many the shop carried would fit her properly. If you don't have a good fitting mask, you will be unhappy. If you are unhappy, you will buy a different mask. Suddenly you have just doubled the price of the mask (at least).
I purchased the mask I usually use in 1999. I have used it for 99% of my diving since then, including ocean dives, fresh water dives, and countless pool sessions with students. I would guess it has been used a few thousand times. It is in perfect condition. I don't remember how much I paid for it, but on a per use basis, it is pennies. An excellent, good-fitting mask can last you a lifetime. Purchase the right one from the start, and you will be much happier in the long run.