Hiya,
A doula can give great support but in the event of something happening I'm afraid that she will have very little at her disposal. A doula is a non-medical professional and as such she would not and should not have the necessary stuff in the event of an emergency.
Whilst the likelihood of an emergency happening are low they nevertheless exist for all women having babies not just VBACers.
In these difficult economical times, many mother, like you, are finding it harder and harder to achieve what they desperately want. I strongly urge you to look at all your resources, within your family and without. Perhaps a payment plan for a midwife would work. You will never know until you try it out. There are good midwives that understand the pressures and are willing to work it out with women who are financially strapped.
I think the most important thing is that you are safe and that you feel safe with whatever decision you ultimately make.
A doula would be a great idea to have around during labour to the tell you when it looks like a good idea to go into the hospital to birth. This would be your best bet, lest expensive and possibly the safest thing to having a midwife present. The only difficulty is regarding the hospital if they allow doulas or not.
Keep searching and something will come up.
Many people are reading the forums and one day someone will post their thoughts too.
Good luck!
Love and hope
Lia
xxx