Alterations

I'm unsure the costs for those, but I went in for my DB alterations a month ago and this is what they charged me:

I’m 5’4” wearing 4” heels. The dress has 3 layers (2 which are tulle).
I got a size 4, but the lady said I should have gotten a size 2. Unfortunately, that would have taken months to receive so getting size 4 was my safest option.
Taking in neckline $45

Taking up shoulders (cause I’m still short!) $35

Take in seams $65

Reshape arm hole (cause taking up shoulders) $20

Hem $150

Take in side seams $60

Bustle $50

Add cups $20

The cost was a lot higher than what I was expecting. I don't have any fears that it won't come out right cause I had such a great experience with the seamstress the day of my first alterations appointment and during my bridal dress appointment. I pick up my dress at the end of the month so I'll have a better assessment of their work.

This dress is SO beautiful, Amber
It's difficult to tell how much is reasonable for alterations as prices can vary with the complexity of the job. I would recommend you reach out to another local seamstress and get pricing for comparison. Yelp is a great place to find some highly reviewed seamstresses in your area!
Where about are you based?