There is nothing you can do about the bond amount at this point. The reason it is set at $50,000 is the State is requesting an emergency protective order be placed on you. Once you are arrested the Judge will issue the order and your bond will be reduced, usually to around $1000 (depending on your criminal history). I suggest before you do anything you consult a criminal defense attorney to advise you on the best course of action. Posting a bond in this situation is tricky so a lawyers advise is needed.
There is probably a warrant for your arrest out there (you can contact HPD or HCSO to verify that the warrant actually exists). If you cannot afford what these bondsmen are quoting, you could always contact other bonding companies to see if they would charge you a lower rate or contact some local criminal defense attorneys to see if they think you may qualify for a personal bond in this case. Depending on the alleged facts of this case and your criminal history and ties to the community (as well as the judge's disposition towards a personal bond), a lawyer maybe able to get a bond wherein your promise to appear. The only fee you would pay would be to the lawyer and the Pretrial Services Office for any monitoring fees (if applicable). I would guess that most attorneys would charge less than the 10% you have been quoted. Your other option may be to turn yourself in and sit in jail while awaiting a resolution in your case (this could take several months).
Call some local criminal defense attorneys to see if this is a possibility.
Disclaimer: This answer is provided as a public service and as a general response to a general question, it is not meant, and should not be relied upon as specific legal advice, nor does it create an attorney-client relationship.