Ha! I was in this same situation last Summer, my factory clamp was corroded completely through and my battery was dead.
I was totally unable to find an aftermarket battery clamp for my 99 that would function with the odd setup Toyota put on there. Tried 3 different styles and none of them worked. That's the bad news.
The good news (for me, anyway) was that my local Toyota dealer had a factory clamp in stock and the cost was pretty reasonable, about $25 brand new.
Also if your new battery is taller than the old one (mine was), you may need to get a longer bolt for the front mount and put in some washers for spacing. If you aren't sure what I mean, let me know and I'll take some photos and show you.
Bottom line: Don't waste your time trying to find one at Autozone or Checker or Pep Boys, just get a factory clamp.