http://www.apartmenttherapy.com/moss-mat-feels-good-looks-grea-75565

Only just seen this although it appears to be about 5 years old. There's an article listing how to make your own here:
http://www.iflscience.com/plants-and-animals/how-moss-shower-mat
Although way too much work.

£200 is also far too much for a bath mat, but think how nice moss feels under your feet if you go paddling in a stream or something?