Grey Market: Cameras sold in America with Japanese warranties. Read: No warranty here. It's a little cheaper, but far from worth it, in most cases.
I'd also recommend digital. It gives you so much more opportunity to learn from what you did, as well as shoot without reservation. When I started shooting, it was film, at a race track. I went through 7-12 rolls of film per night (at $6 per roll, plus $8 developing). A year and a half ago, I broke down and bought a DSLR, and the 35mm hasn't left the dark corners of my camera bag since.
I bought it because I was headed to Hawaii and knew that the cost of getting into the new camera (I spent about $2K after camera/lenses/bags/extras) would be exceeded by developing costs in a very short time. I ended up shooting 1300 shots in Hawaii in that ten days. By now, I've shot nearly 9,000 photos through it. I get instant feedback, and can adjust and re-shoot on the spot if I have any problems. I can also carry them over to my computer, and not lose any sharpness because it went to print first. The only time I've ever had film shots as sharp as my digital shots was when I shot with high end film, and paid to have them scanned by a $100,000 drum scanner, at $25 per scanned photo.
One other MAJOR consideration is that you're shooting your tank. If you realized how many bad shots happen in a reef tank.... oh man! I tried a couple rolls of film at my tank once, and will probably never do it again. You can't white balance, you have to buy filters. Everything came out washed out blue, and I ended up with two rolls of trash can filler. Not one shot came out.
For me, it's a no brainer. Go digital, even the pros aren't bothering with film any more. Digital really is that good nowadays. If you can stretch it out, and get into a digital SLR, even better.
