I found a case that I think works pretty well, it's a Lowepro DMC-Z "memory card wallet". I got it at Best Buy for 10.99.
I removed the middle sleeve and modified it a bit to hold slightly longer e-cigs. (the 510 fit fine, but the 901 was just a tiny bit too long, it will fit, but it was tight against the zipper.) If anyone is interested I can try to post a pic if I'm able (I'm new to the site, which has been great by the way!).
Anyway, I like it because it's just about as small as I could possibly get and still carry what I wanted, which is 3-4 fully assembled e-cigs (901's and/or 510's), 4 3ml dropper bottles for juice, plus a 1-2 extra batteries. It's a tight fit, but it's made of neoprene, so it stretches.
I wanted something that would have extras but still be able to fit in my front pants pocket, like a wallet. I think it's going to work well for me.
I hope that helps someone else, as I've gotten many good ideas from this site so far myself!