M.G.
I have not tried them personally, but am thinking of trying out some at some point -
There is a Clairol Shimmer Lights that has good reviews (seems quite budget friendly) but then there is an Aveda product for grey hair that I bet is very nice. I have a relative who is a hair stylist who works with Aveda products and I've received gifts from her in the past and love their products (always smell nice). She swears the shampoos make a difference (over regular ones). She may be biased of course (they use all the products at their salon). Blue Malva I think it is called. It's pricey, but I do find you don't have to use much of their product, or maybe I'm careful with it.
A friend of mine uses a product for silver hair (truly silver) and it keeps the brassiness out - she has to put it in every few weeks. I am not sure if it is a shampoo though. Seems to me it's more of a treatment. Your stylist should be able to guide you - I think she has it done at her salon (for whatever she has done). It may actually be more of a rinse? She is transitioning so may actually have some color still in it.
Good luck :)