Expensive. We spend $100s on minor things each trip and if you are looking at surgery it easily surpasses a couple $1000 in large city areas. You have to decide how far you want to go to save a pet. $300-$500 for basic tests, exams, and antibiotics or painkillers is a good starting place. Teeth issues will probably cost more and are quite common, particularly in poorer bred chinchillas like those that often show up in petstores. A good breeder usually screens for dental issues and doesn't continue breeding any that show problems. It can be difficult to keep track of though because many breeders only breed a chinchilla until it's 2-3 years old and then move on to the next generation. They may not see a problem before they are done using that chin and have sent it off to a pet home.