Do it! It doesn't have to be expensive, as long as you do your research. Also, be careful about which company you get certified with - PADI is the way to go, but I think NAUI is good too. DO NOT get SSI certified though, it's way more expensive and no better. I happen to know two of the three people who started SSI, and I can tell you from experience (I'm SSI certified as well), that it is the wrong path to take. You should definitely get certified though!!! It's so awesome!
Anyway, here's my list - not everything, of course, but a few. The first two are technically in tidepools, but... well, you can just deal.
Invasive lionfish in Mexico
. The dive shop we rented from had an awesome lionfish cookbook though! They're trying to teach locals how to catch and prep them safely to try to reduce numbers, since they have no natural predators. Pretty cool!
A CRAZY green xanthogrammica in nor cal.
These are from a couple dives in Monterey
And this last one is from the side of a dock in Charleston, OR
Other notable sightings include a big nurse shark, baby horned sharks (which are ADORABLE), a pair of dolphins teaching their baby to hunt with a school of jacks (which was also ADORABLE), but, alas, no pictures on this computer. So yeah, GET CERTIFIED!