Anyone know how much it costs?

Maxine is a shepherd/chow mix and is a very grumpy dog. She growls and scowls and bites almost everyone. The past couple days, she's been unable to even get up from laying down. This poor dog must be in so much pain, that even as a grouch, she's getting meaner and meaner. My fiance's mom is someone that this dog would NEVER bite. She was rubbing Maxine's back feet and Maxine bit her. She's only 11, but if it's this poor dog's time to go, I have the feeling that my fiance's parents and brothers will make her do it (take Maxine on a one-way trip to the vet). I told her I would go with her. Does anyone have any insight on euthanization costs, or what we can expect as charges from the vet? Also, does anyone know of a low-cost clinic that might do it on the cheap?