It was $50 to raise the hem of a flower girl dress by a couple inches and resizing a blazer is much more complicated so I think it would be safe to believe it would be quite a bit more than $50. They were able to give me an estimate over the phone, so you might want to give them a call with your project details.
I had the sleeves of a suit jacket shortened for $35, so if you need that and other adjustments I would imagine it would be upwards of $35.
I haven't done anything like that, so you'd have to take it in for the seamstress to look at it.
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