I thought I'd share this find.. I found one at the Vancouver Home Show last year, and I've been using it for a year with excellent results...
The Nimbus Watermaker costs approximately $100 and is perfect for renters. You get a great little RO unit that attaches to your sink faucet. it takes approximately 8 hours for 5 gallons to be produced. I run it while I'm at work or when I'm sleeping.
The downside is it doesn't produce much.. also, you have to replace the membrane after a year... If you live in a permanent residence this wouldn't be your best choice, but for me this has saved me many trips to the grocery story for water...
A website with some information:
http://www.crystalline.com.au/page41a.htm
http://shop.store.yahoo.com/aquamall...minrevoss.html