Hi Laura,
Welcome to WAMAS!
As for UV - I run a 40 watt Current system on my tank all day, every day. When I started in the salt hobby in 2000, the so called "trend" I was told was that most people were moving away from UV because it would destroy all the beneficial things important to keeping a reef tank. I can say that I went without one in my original 125 AND twice a year during spring and fall when I would see biggest tank temp swings (as either house heat or AC wasn't running as often) my tangs would show signs of ick. In early 2006, after doing some research on people running UV vs. those not, I felt based on my research I would run UV on my new 215 I was setting up. I believe it's one of the best things I've done for my system. My powder brown and regal/blue hippo so no signs of ick ever in new tank and those fish are prone to showing ick first. AND I don't see any loss of life or colors of corals & my pair of manderins don't seem to mind UV as they have been in the tank for 2 + years and find plenty live pods to eat.
Sure water quality is a key - and UV will help improve water quality. You don't have to spend $300 on a unit. If you can't find a quality one at a local store, you can always looks here for ones that start at $118 + ship.
Good luck in your research.