I think this thread should be one of those marked "important" in red that are always at the top of the thread list. So many times, I see threads in this section from people looking for help because they can't afford to take their pet to the vet. This link is a great resource for them - and all of us who occasionally have tough times!
Great page! The other option that many of the folks on this forum can use if you haven't tried it.....
I've negotiated discounts with my vet based on the "volume discount" plan. When I moved to where I currently live, I interviewed vets that were willing to work with my critter habits - I am owned by many, have ferals neutered and released / adopted, and typically take in the sick and injured ones. If I didn't do this, or lived in a city and had to pay city prices (I also have the country vet discounted rates), I couldn't afford to do what I do. I work with the animal control agencies to borrow cages to catch the ferals, and they are so happy that I'm doing it and they don't have to do it that they lend me their equipment.
If you don't ask for a discount or free services, you will never receive them!
I've gotten neutering services negotiated to $25 per cat (dogs are more). Annual vaccinations (full range of them) are $30 per cat. Many things have no fees at all - I can sometimes talk him into free neuterings on ferals if he's having a good month himself.