Now, I know that it can be a bit annoying to find something that is already expensive just to hand it off to someone and pay extra… so I say hit those thrift stores hard and strong. I personally was just at a store, found a dress and wasnt really sure what to look for when it came to possible tailoring options, so I asked a person that worked there, and she gave me a simple solution and I went home and did it myself, super domestic and super easy.
As for tailors, I would say just ask around, find the best price etc… maybe even ask your mama or find a youtube video! The options are endless!
Have fun to the new experience of shopping!