On my last Vet visit I explained to the doc that I could not afford their prices and would be getting any prescription at Sam's Club since they started filling them. Not wanting to lose out on the money my Vet agreed to match whatever price Sam's or any other place offered.
Most Vets do have a heart you just need to explain your situation to them. Most will help you out.
"The more people I meet, the more I like my dog"