Call around to different lawyers' offices. Many have associates who work for them and for whom they will charge lesser fees. You are right to be concerned because this case is serious and needs work - including the help of an investigator. The bond is the secondary concern.
A past false accusation may be very helpful evidence for your brother. If you're eligble for Legal Aid, try them. Otherwise, if you don't trust the public defenders (and even your past expefrience aside, you should), shop around for a reasonably priced criminal defense lawyer. One lawyer you might try is Tony Luti, (323) 960-2600, www.lutilaw.com.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.