This is just me, but I'd recommend saving your money and using it for something a bit more useful and/or versatile. Wah pedals sound great for funk and the occasional classic rock solo, and... well, that's about it.
If I'm going to actually give the kind of advice you're looking for, I've got a Vox wah that I like pretty well. It may not be the most useful effect I've got, but it does that one trick very well.