The Mares avanti quattros are good all-around fins. There are a couple of different models (superchannel is one you might like, being Superman) and they all seem more or less the same. If you're going for warm water diving I personally prefer full foot fins. I use mine way more than I use my open heel fins, but I live in a warm climate and I don't mind walking barefoot in most places. I think scubatoys has them on sale for about $60. The open heel avantis are a little more. They're good middle-of-the-road blade fins, just about neutral and kind of a medium stiffness. Please don't spend $200 on split fins before your class, and if the salesman tries to sell them to you, ask him if you can bring them back once you get good enough at diving to realize how much they suck.
You probably have to try on the mask, and as everyone else says, get the cheapest snorkel you can find. Oddly enough, the only dive gear I've ever had stolen was a crappy snorkel I left in my gear bag during a dive; I was actually kind of sad to see it go. It was pieced together from a really old garage sale special and a silicone mouthpiece. Maybe my next one will be a DIY out of PVC pipe and an old regulator mouthpiece.
You might find that there's an incentive to buy from the LDS in connection with the class; one of the local shops does that here. Conversely, you might find a serious vibe if you show up with gear purchased elsewhere. It happened to me, and i've heard some horror stories about shops charging a $75 "inspection fee" for snorkeling gear brought in to an OW class. That's a good one, sometimes I wonder how guys like that can keep a straight face.
Anyhow, have a great time with your class and try not to spend too much on gear at first.