Those LEDs come with one of Custom's lighting fixtures. I believe the 48" one comes with 4 of them. They're like spot lights I think. I was thinking of getting the fixture, but settled on something cheaper. I have one of those "miracle beam" kits with blue and purple LEDs that do well for a night time setting, and they look cool too with 5 light beams all over the place.
$28 on eBay Joe. That seems like an awful lot for a blue LED. If you can find a decent diagram I'm sure you can make one for a quarter of the price. Since it fits under the hood it's invisible anyway.
LMK what you decide to do... cool idea. Most of the time when I'm at home my tank light is off anyway