corset: damselinthisdress on etsy. She is AMAZING!!! She also did a wonderful commish for me from an outfit I designed. Wonderful quality and great to work with. I own 3 of her corsets and I am a customer for life!
I made the hair deals(got everything from Hobby Lobby and Micheals), modded the gloves, goggles and gun(with vast amounts of help from ~CoughffinKnail ), modded the belt and attached all the bottles. (whats an apothecary without bottles!? hehe) And the aqua belt strap I found on a renfair costume site.
The bottles I got from a really super cool story on etsy that I can't remember at the moment, lol. But if you search poisons or apothecary you should be able to find it.
As for other custom fitters, what specifically are you wanting made? Let me know if you need anything else! Always excited to help fellow steamers/cosplayers