I'm beginning initial research on folding bikes for a commute. I take Metra's UPN from Ravenswood to Davis and onto Northwestern University (north campus). I'm looking forward to a reasonable quality, but I can be flexible in my requirements given my budget.
Richard (original poster):
Did you ever get your folder? If not, someone just posted a $250 Dahon Mariner for sale on the Chainlink Forum HERE.
I've got a Dahon Speed 8 that I bought from Rapid Transit back in 2003. The hinges have held up well, and it's been a very reliable bike. I don't put tons of mileage on it - probably a few hundred miles a year. I have started seeing folders in more shops in the last couple of years, so I wouldn't be surprised if some north suburban shops have them now.
To follow up. I got the folding bike mentioned by Thunder Snow. It rides pretty well. In fact I took it from Northwestern to River North via the ELT / Gleenwood / Greenview / Devon / Lakeview / Rosemont / Winthrop / LFT.