I have never seen these products on sale here, but I have read about them in websites. I am curious about them but I don't know where I can get them. Perhaps in an hairdressers' supplies shop.
A while ago I bought a conditioner for grey, white or platinum blonde hair. It is called Touch of Silver by Pro:voke and it is meant to nourish your hair while giving it radiance.
The ingredients' list is far too long, but appart from the usual, it has sunflowerseed extract, wheat amino acids, citric acid, magnesium nitrate and acid violet 43. It is an OK conditioner, can't say anymore than that. I haven't noticed anything special about my hair after using it.
I don't know if I can be asked to buy specific products for grey hair. As for volume and shine,yes; and if you're looking for a 'mature' hair line, I would recommend Kerastase. I use the shampoo and I love it. It is expensive but you only need a little bit at a time, so it lasts. I will buy the hair masque, which is quite pricey, but at the moment I am finishing a couple of bottles of conditioner first.
When I had long dark brown hair (long time ago) I used to rinse it in lukewarm water with acouple of tablespoons of white wine vinegar;but has my hair now needs more moisture I am reluctant to use vinegar.I might try it just once to see if it adds more shine.