The best one is the 200mW Red one they offer, it is only $44 too. It looks like you ordered one of those though. With the extra money you can pick up a pair of goggles from shop.stonetek.org, you will want goggles for that power.
If this is for your son like the other thread, do him right and get him a Leadlight. Leadlights have unmatched build quality and beam specs for a ~5mw green laser. Besides, do you really want your boy running around with something that can blind him?