Not every dress needs the same amount of alterations.
I can break down the average cost for each particular adjustment. But you will find that the range is so broad it may not be very helpful.
If you email a good picture of your gown while you wearing it, than the seamstress will be able to give you a more accurate estimate.
This is an example of the range of price to adjust the hem:
$100-250. The way the price is determined is the type of fabric, beadwork or trim (lace) at the bottom, layers, and will it have to be hemmed from the waist.
Keep in mind that the hem is usually the most expensive alteration, so if your on a tight budget and your short, don’t buy a dress with a lot of detail at the bottom that will have to be moved.
Side seams range from $35.00-$65.00 Re-beading is expensive! The more beadwork, the higher the price.
Bustling ranges from $25.00-$65.00
As you can see, it’s a broad range with many determining factors.
Ask your seamstress if she’s insured. If she is not, the price may be lower. However it may cost you more in the long run if something happens to your gown while in her care!