How cheap are you wanting to go? I've had great luck with aquaneat blue/white led lights. The main failure point people complain about is the switch, but they unplug and are easily replaced. I have had a bunch of these lights in different lengths long term now, and I've only had one switch fail. The manufacturer is CLL pet supply and they have upgraded the switches. They sent me bunch of replacement switches at no charge to me and I only needed one. I just emailed them directly. Also I would highly recommend running two 36 inch lights on a 72 inch tank. They are more usable for other tanks later on, cheaper to replace if you have a problem with one, and there are simply way more options out there. 72's seem to be a lot less common.