wedding dress alteration costs?

I have been quoted $2300 for alterations on a wedding dress that cost $3500, it need to be taken up ( 2 layers with small train ) a small area added to back to make dress more comfortable with a very small amount of beading ( approx 2 inches by 4 inches ). I feel as though Im being over charged but with wedding 6 weeks away I have no other options , what are your thoughts on this