I think there is a thread a few pages back on doulas/cbes or b&b, about choosing a doula.
Any doula worth her salt would be great in a VBAC. I have 2 VBAC moms right now, one is due next week and one is due in August.
I'd interview some doulas -- and I'm a big believer in whether or not you just click, as opposed to the more clinical questions of how many births have you attended, where are you certified, etc. I interviewed like 6 doulas for my dd's birth but didn't find the right one until a month before she was born. Obvs a doula will see you naked, puking, pooping, leaking amniotic fluid, etc, so you want to be comfortable with her.
Good luck.
ETA: try the ALACE website (
www.alace.org) or the DONA website (
www.dona.org) if you are looking for a place to get started.