Well, there's www.fabriconnection.com
- and she's an MDC mama, too. For PUL, you can try Janelle's PUL's www.janellespuls.com.
Momufactured on e-bay usually has lots of good diaper fabrics, too.
So, what are you looking for as far as diaper-making supplies? Fabrics? Aplix? Snaps? Patterns? There's different "best sources" for each of these things....
Oh, I almost forgot about the sewingsupplycoop on yahoo - http://groups.yahoo.com/group/sewingsupplycoop/
Probably the best prices on elastic & touchtape.