Erin,
Since you are on a tight budget, I suggest looking for a free trans group meeting. There you can network with people who may be in the same situation.
In my experience, there are very few Primary Care Physicians who will prescribe HRT from informed consent alone. It may be more expedient to find a low cost therapist who will give you the hormone letter with just a few counseling sessions. Look for a therapist who advertises a sliding scale fee. Usually less for those on a tight budget.