Custom tie and vest for tuxedo?

Hello. So, the color of my dress is a very soft ivory. The designer says that if my FH wears white it will be too stark and she says the ivories often look too yellow. She suggested buying a piece of the fabric that my dress was made with and having a seamstress make him a shirt and vest with the material so that he matches me exactly.

Has anyone done this and if so, was it really pricey to do? Can you recommend a seamstress who could do this (my place - Kleinfeilds - doesn't do it)?

How about going a shade darker, like a champagne color ?
It is still in the same color family.
All that matters is that your FH wears a different color to differentiate him from the rest of the BP.