For fresh water a cheap easy way is shop fixtures from Lowes or Home Depot. A couple cheap 36" fixtures would work good on a 180. If you feel you need it buy aquarium bulbs for a higher kelvin rating like 10k but the 65k bulbs you can but there look pretty decent. If you want moon lights buy some strands of blue led xmas lights from walmart for 13 bux. I stuffed the leds in my fixtures that came with my tank it it is the perfect amount of light at night for a couple hours.
Like I want live plants it's for freshwater. my local pet store owner is trying to get me to buy a $1200 light for 600 but I don't know anything about it. I don't want to spend a lot on just the light.
Dont buy a $600 light! Just get some T5HO's. Aquatraders.com seems to be a great place to get lights. Or check out ebay. Look up t5 ho. The lights for indoor growing are pretty nice. For low light plants t-8's are fine. if you add to much light with plants with out co2 you will have algae problems
I am still in the dark ages using t-8 bulbs. But I think everything looks great. You can really spend a lot of money for lights. I don't think there is really a right or wrong way for fish. But if you are growing plants or have coral then there are must requirements.