When I was in college and had a very very small income, no help from my parents, etc. I adopted a dog that needed emergency vet care. I had applied for a credit card a month earlier and just got it in the mail. I had a credit line of $250 (this was 20+ years ago). Helping my dog was the first thing I used that credit card for.
I just recently dropped $800 for my dog's oral surgery. I had to work a few extra shifts to pay for it, but seeing my dog feeling better, it was worth it. Pets are totally dependent on us for their care and well-being.
And if you can't afford the vet, and can't find a rescue place, please don't let it suffer any further. That snake is suffering. At least pay the $25 or whatever to get it euthanized. (Sorry that may be an unpopular suggestion, but it's a humane option)