I'm relatively new to this site but have seen many oldtimers here suggest to those who are in financial need (for vet bills), to contact this company:http://www.carecredit.com/
Many seem to have used them to help with crazy high Vet bills and say good things about them. I never have but it appears that they lend you the money and then you have a certain time period to pay it back.......and it it's within a certain period there's no interest (quite a long period, actually - 18 months or more?)
You'd have to ask your Vet clinic, I think, if they would be willing to accept payment this way, that seems to be what I've read? You might want to call Care Credit and get the details because I'm not really sure; if they're loaning you the money I'm not sure what the Vet has to do with things; maybe they require the Vet to verify the legitimacy of the Vet bills or something?
This is another site that helps with financial costs for pets. I used them once many years ago, when I had sky-high vet bills from a very ill stray cat I rescued:http://www.imom.org/
Here is another one that has a good reputation; I actually donated some money to them a couple of years ago, when I was in a better financial position:http://felineoutreach.org/Assistance.asp
OOPS - I just read on the Feline Outreach site that they're currently unable to provide financial assistance but they do have a link of other organizations/agencies that may be able to help, here is that link:http://felineoutreach.org/Organizations.asp
Hope this helps