Congratulations on your pregnancy and for seeking the support of a doula for the birth of your baby!
I recommend that you check out DoulaMatch.net, as well as the provider listings page of doula traning program websites (ie. DONA, toLabor, etc. Just google doula training program, and you'll find plenty!).
You may find new doulas willing to offer you their services on a volunteer basis, though it is generally a courtesy to offer a stipend for parking and gas.
Best of luck to you!
Sweet Song Doula
Check me out on DoulaMatch!