I second the "wait for it" approach - I saw 2 fibreglass sinks (Ottawa, Canada, and Niagara Falls, Canada) before I found one that I could use - a Delta 2x4 sink with all the fittings. It took about a year for one small enough to use to come up. (two different towns - but my parents live in one, I'm in the other - people selling sometimes don't mind holding on to things for a few weeks if you are travelling)
I did pay about 40% of retail price for my sink, but got lots of stuff thrown in for free - so in the end I think I got a really good deal.
fyi, I look in ottawa.kijiji.ca and a local used-ottawa.com site. Craigslist seems pretty slow here. Keep your eyes peeled, and look in different places.
JohnS.