we had one in Stockholm in the university.

a couple of things of Stockholm that made it work:

1. there are no gang bathrooms ... each corridor had three separate locking rooms each with it's own single toilet and sink. there were shared by men and women.
2. we had a temporary free-standing plastic shower installed in one of them.
3. all Stockholm bathrooms have a drain in the middle of the floor.
4. the hot and cold water were installed into the lines that ran from wall to the bottom of the sink.
5. a PVC pipe connected the drain of the shower to the drain in the floor
6. total cost was roughly 3000SEK for the shower (€300/400 USD) and maybe 1000 SEK for the other pipes (two water lines ... think wall to ceramic part on a toilet ... and a roughly 1" PVC drain with a couple of elbows ... and cutting a drain hole in drain cover in the bathroom floor) and installation
7. In the end it was quite durable, maybe 6-8 people used it per day 5 days/week for the 2.5 years I was there without issue.
8. In was a royal ***** job to have to clean out the drain

kind of like this

http://www.diynetwork.com/how-to/how...kit/index.html

but the walls looked a little more durable but not enough to get any action in the shower if you know what I mean

more like this for home depot:

http://www.homedepot.com/p/t/1003859...3#.UW0acIVD79o

not a bad price if you ask me.