If it's just for a small shower room, contact any industrial/contract flooring firms near you and ask if they have any off-cuts or roll-ends of non-slip flooring lying around from big jobs.
It's been costed into the price of the job, but these guys throw out nothing - cos it'll always come in handy for folk needing just a wee bit for a small area.
You get it at a decent price, and they get a few notes for the weekend. WooHoo!