Crazy alteration price...Please help!

My dress came in an i went to get my 1st fitting.l am adding very small off the shoulder straps-paid $100 for the extra trim. The dress cost around 975 with tax. Put down a 500 deposit. When she started adding up my alteration fees they came to $400 plus the $100 I am paying for the extra material. This is whats being done:
straps: 100 for fabric + 75 to make straps
75 to make a straight neckline a sweetheart.
75 to add 4 more loops to the corset back so it will tie a bit lower than now
175 to hem

Does this seem exorbitant to anyone? With the balance of my dress plus the alterations it is now like I never even put a deposit down!

Unfortunately it seems about right to me.

Yuo could take it somewhere else for a quote but I dont know that it will make that much of a difference.