What about some vitamin E oil?? Pregnant chicks use it lol. Or you can get some special maternity oil or cream. Wifes popped out 2 kids and put that stuff on religously and has not one stretch mark. Her friends have also used it with great success. Its fairly cheap considering it works great.
Also read cocoa butter and then some vitamin E oil after can reduce the appearance of exisiting stretch marks i thats what your looking for should be cheap to try, man look it up.