there are cheap and viable options for you.
Go and make an appointment with an Optomertrist. Talk to a professional.
Discuss with him using or trialing contact lenses, I have surfed with them for years, my prescription is -5.5 diopter in both eyes, i.e I 'm almost as blind as a bat otherwise.
My Optomertrist recommended I use a brand called Johnson & Johnson and the model within their product range is called "Surevue". They are "monthly disposables". This means you buy them in small boxes of 6 lenses, you wear them as a set for normally about 1 month before you simply thrown them out and wear a new pair. This way a box will last you about 3 months. I buy 2 boxes at a time normally, in my country this costs me about $60 per 3 month period.
The reason behind the relatively new idea of disposables is - lenses get pitted, they wear and get protein deposits on them. By throwing them out rather than attempting to clean them- you get nice sterile new lenses each month. i.e. far less chance of eye infections caused by poor hygiene & cleaning methods.
Provided the lenses are fitted properly and sized correctly by a professional, there is little chance of you losing them in the water. Your natural eye saliene solution acts like a suction system to hold the lenses onto your eye. They're a very clever and very simple system.
Provided you remember to squint when getting nailed by spray etc when wiping out, and close your eyes when diving under the water or duck-diving etc (for me this is instinctive now) You won't lose your lenses. Simple.
I suggest you get a trial packet (most Optomertrists allow you to try product samples given to them by the Companies who make them) get shown how to put them in & take them out...then go home and stick your head under the shower while wearing them and see for yourself.
The reason why Contacts are the best option for surfing rather than "waterproof glasses" is; with contacts you have complete periperal vision - this is important for a surfer or else how can you gauge distance in an instant without having to turn you head to look, be it a falling wave lip, a set approching, or someone dropping in on your wave you've just seen out of the corner of your eye beside you.
With glasses of any sort- you only have perfect vision when looking through them, so, you have to turn your head all the time to look at things.
I'll illustrate this now- you can see your monitor in front of you perfectly with glasses right? Now; without moving your head look in a different direction outside the physical frame of your glasses, perhaps to your side or up at a picture on your wall. You can't see a thing in focus eh?
That's where contacts are good, you have perfect periferal vision in all directions without having to move your head to achieve it. People who don't wear glasses can't understand this. For those who do it's instinctive, you turn your head to look at everything. You don't even realise you're doing it.
Periferal vision is critical for surfers and I imagine others involved in many sports like soccer, basketball etc where you need to know what's going on around you and be able to judge distances as you participate in the sport.
I hope that makes sense...and sorry for the novel.