Hmmm...Shades, you bring up a good point. Why is the drive consuming so much power? Well, who knows. Actually, I'm an electrical engineer by profession, I should know the answer, but I don't know anything about how hard drives and stuff work.
Anyway, here's the deal. The enclosure is from Granite Digital, an excellent company with fabulous customer support. I love their products. I've been thinking about it and I believe I have come up with the best solution. I've asked them if i can return the enclosure I have for store credit and use it to buy a 2-bay enclosure of the same type. Why? Because, first of all, their 2-bay enclosure comes with a built in 300w power supply. Secondly, my enclosure cost about $70 and their 2-bay enclosure is on sale for $100. So it wouldn't cost me that much in the end anyway. I also have a couple of spare 500gb drives lying around that could be used. So, that's my solution.
As for the drive consuming a lot of power, the answer I got from Granite Digital is that the external power supply that comes with the unit can support most drives, but with the drives getting so big now 1-2TB, their power consumption is getting a little too big for these power supplies. The model of this power supply is listed for 34W, but I don't know what that actually means. I haven't read anywhere of a hard drive using 34W of power or even close to it, but the actual values of all these things are always vastly different than their listed values. So whatever.