my neighbors have underwater light from greenmonsterfishinglight.com and personally i would not recommend them. both of my neighbors have had issues of only one of the two lights working at a time. the lights look great and attract fish but just seem to unreliable to me. i would look at a different company. deepglow.com looks to have a very good light but i have personally not tried or seen them. as for price most of the upper end permanent lights most cost around $350.
if any one in your area build custom neon signs..... you can always go down and have them build you a couple straight tubes with the elements on top incased in clear acrilic tubes that are submersable........ burn time is about 4-5 years about 8-10 hours a day..... and fairly cheap. or go find someone that builds pools and by a couple of there pool lights....... plug-n-play application?