i did some research, and apparently spaying rabbits costs anywhere between $55 and $180
also, i dont think u should spay her cuz u dont know how old she is...spaying a rabbit over 6 years is dangerous...they are prefered to be spayed between 4 and 6 months old, and any time before that is also risky...
the only thing i could find about being dangerous if the rabbit isnt spayed is the fact that it would be at a high risk of cancer....i also found that they make better companions as altered rabbits are calmer and less destructive...
if u do want to spay her, u should take her to a rabbit experienced vet who could tell u her approximate age...