I am really skeptical about those, but I am also not as experienced as some of the members on this site.
I read a little of what this guy says about these, but still can't understand how only 65 watts can have the output of a 500 watt bulb.
I honestly don't think these would do well for saltwater. You said you have about $300. to work with and you should be able to get a nice package through Greg with that.

HTH,
Jenn