A bit over a year ago, I got mine from Rapid Eyewear from the UK.
Pick the sport (RC Model Aircraft), and let them know your prescription.
You get 4 different outer lenses, that fit over your untinted prescription.
The 4 lenses you get are different for different sports, sometimes polarized sometimes not.
I'll use a medium one for bright sun, but anything less than that switch it to the yellow, contrast enhancing one, and it really helps make the contrast pop, helping out a bunch.
I like them, although I've heard good things as well from other brands mentioned here too.