MH - where should i get em?

[Quinn]

howdy folks.
just getting going here with a 90g, thinking about 2 250w MH. obviously they're well expensive, i'm wondering what the cheapest place to buy would be. i'm planning to build my own canopy, by the way.
and another thing, HD sells MH lighting, and it's much cheaper than the stuff on the MO sites. is there something about it that makes it useless to reefers?