Just so you'll know, Mystery snails do not appear in pink. You will see Purple, but not very often.
I've kept as many as 17 different snail species at one time; the critters fascinate me for some reason. But the only fresh water snails I've ever seen in fresh water aquaria which may appear to be pink or red are the small ramshorn species. They're also seen in blues and many shades of brown, even one called Leopard, which has a spotted shell.
The little ramshorn snails that are pink or red have pink or red skin which shows through some of their shells. Their red blood pigment shows too; they have red heamoglobin in their blood.
Mystery snail's blood is green, based on haemocyanin ( common to most snails), so there won't be any red or pink Mysteries due to the blood pigment showing through. Perhaps one day someone will find, or genetically engineer, a pink Mystery. Be neat if that happens.
~I am willing to ship plants/stuff other than livestock, to any member, from retail stores or private sales. Also willing to pickup/deliver. Modest fee + my costs.
Please PM for details.