Laser for continuous operation

A friend of mine is opening a beach bar / dive shop, it is located a bit further up the beach than the other places so misses out on passing trade. Infact it would be easy to miss it completely as the beach curves away inshore so there is no direct line of sight to the property from the main strip.
The Idea is to install a "marker" by pointing a laser into the air. You could then give directions - "look for the laser".

Now before anyone jumps on me the location is in the Philippines, the nearest airport / flightpath is a 4 hour drive away.

I have been looking at DX modules which show everything from 5-200mW but many / most do not appear to be intended for continuous operation. What is the limiting factor? - I could do heatsinking by fixing it to a scafold pole or other large bit of metal, or is there another way of reducing the output?

ps pricewise - I am thinking less than $50 as it would be a fun gift from me rather than signed off against a big marketing budget.

Thoughts:twothumbs

First thought is, go with a green laser.
Second thought is, perhaps make it flash, scan, or do a pattern, if you are really looking for a project.
Third thought: heatsinking is crucial. Be sure to heatsink the entire housing too, not just the diode, but the crystals. And don't pot mod anything, and perhaps buy a few backup modules if you buy 'em from one of the cheaper places. Then, you can have an exact replacement IF it does go bad, and if it doesn't go out after a year, you have some toys to play with!
fourth thought: make sure it is pretty much impossible for someone to look into.

Have fun!