Where to buy lower tooth rear sprockets?

[isaac]

I know this has been gone over, but I've searched and can't find where to actually buy the damn things. I usually go through ebay or bikebandit for this kind of stuff. I'm looking for a 38 tooth rear.

Of course I'm sure a few of you guys are thinking about how a 38 tooth won't work and all. Too tall, not enough power on the open road. Keep in mind I'm in Florida. We're pretty flat here. I've had a 16 tooth front for a few hundred miles and it's a nice change but it's not low enough revs for me on the 50mph roads. That's just how I like it. I don't care about the marginal changes in acceleration because this thing's not beating much anyway and I probably mitigated it with all the mods I've done.

So ideas? Thanks!