Call around in your city and ask for prices. If you do decide to go for it be sure the doctor is reputable. You don't want your stretch marks to get worse.
I have not known anyone who has had stretch marks removed - I have heard about though. I believe it would be cosmetic surgery and I am betting it would be expensive anywhere.
As you have just had your baby you may want to give yourself some time as they may go away on their own.