Around 80percent of female buns will get uterine cancer by the age of 3 if they are not spayed. Its very recommended because of this that you spay her. Cancer treatments are going to cost a lot more and are going to be much harder on her body than spaying her when shes of age.
Definitely ask the shelter nearby if they know of any rabbit certified vets who can spay your bun. Ask the vet about prices, and how many rabbits they have worked on. Although scary, its best to also ask how many rabbits died on the table during their spays. If the vet hasnt worked on too many rabbits, dont use that vet. If the vet is not certified, dont use that vet. If the vet has had more than 1percent die on the table, dont use that vet. You might have to do a lot of searching to find the perfect vet for your bunny, and might have to drive farther than expected for that perfect vet, but it will be well worth it to have a happy and healthy bunny 