I picked my wedding dress up at the weekend. I am not getting married until...

I picked my wedding dress up at the weekend. I am not getting married until next December but the dress came in a lot earlier than expected. The only alterations that need doing is someway of lifting the train for the reception as it has nothing at the moment. The shop have said that I can have a bustle made when I go back in September for alterations but couldn't give me a price. This is literally the only thing that needs doing. My question is how much can I expect to pay for this to be done? The train isn't very long. X