White Bump on my min-pin tongue

Question
I have a mini pincher 19months old. I notice 2 weeks ago he has a small white bump on his tongue. (It is smaller than a pee, but noticeable) I took him to the vet yesterday they said it was either a calcium deposit or cancer. They said if it was a calcium deposit it would go away by itself. They said I should get a biopsy that would cost $859.00, which is high I think.
My questions are if anyone can help me, please.
1)Can anyone give me any incite on this?
2)To my understand cancer spots are usually black not white, is this true?
3)Has anyone had a dog with a white spot on there tongue and found out what it was?
4)Do you think $859 is high for a Biopsy?


Answer
April,  I forgot to include the following information:

White spots on a dark tongue may occur if your pet has been licking irritating chemicals or even plastic, which may cause allergic reactions, says Steven A. Melman, V.M.D., a veterinary dermatologist in private practice in Potomac, Maryland, and author of Skin Diseases of Dogs and Cats. But in some cases, white marks signal immune system problems, he adds.

Therefore, concentrate on building your dog's immune system up with a good human grade food, Missing Link, olive oil, fish oil, advocado, organic eggs, organic whole yogurt, cooked veggies (no onions, grapes or raisins), etc.