You and your optometrist are the best judges as to whether or not you would benefit from having prescription lenses in your mask. You stated that aside from the bubbles and leaky mask, you could see clearly underwater. TMHeimer made a good point, that you might not really need prescription lenses, either custom ground lenses for your vision or snap in types, and nobody on this site is going to be able to assess your needs better than you. My wife and I both wear glasses, and whereas she absolutely needs the custom prescription lenses to see properly above or below the water, the refractive nature of water eliminates any need for me to use prescription lenses.
Added: If you decide you need the prescription lenses, get good ones and do not shortchange yourself. My wife would say her prescription mask is the most important piece of dive equipment that she owns. As someone else said, you can rent everything else.