Well when you have a 72" tank and want LED's it is hard to mention cheap when trying to light it. Most Leds would run you $700 minimum to make it work out. My 180 has 2 14K BML's that are 3 years old and I ran with my MH, and then added two 20K to replace my 3 x 250w MH.
The ocean revive may be better but not sure 2 fixtures would be enough? And with three you have now moved up to $600
http://www.oceanrevivellc.com/goods.php?id=21