I bought a Dahon Helios P8 used for cheap - $240. After trying various modifications, I now have it as a 66 gear inch single speed using an inexpensive chain tensioner, fenders, rear rack, cut down handlebars with bar ends. Its one of my commuters for my 40 km round trip from home to office - 1/3 of the journey involving elevation changes.

The seatpost will creak but other than that, I am reasonably happy with the bicycle. It goes, reasonably as fast as I care to on that particular bike, it folds so I can place it in the trunk of the car if I meet up with my wife after work, it doesn't run and is reasonably simple to maintain now that it is a singlespeed. Everything works. I know the proprietary wheels will be an issue when its time to replace them. For now I run Schwalbe Kojaks and am very happy with the performance. I do most of the maintenance except for bottom bracket changes and bearing replacements. All the other adjustments and tweaking I can do.

Having said that I think Bike Fridays and Bromptons are at the top of the chain for quality and customizability. The Brommie is highly evolved and highly optimized for a folding bike. There is something about the fold - even with its proprietary parts that is appealing. Having said that, I am fairly agnostic about bike brands. I value bike fit over everything brand and if it works reasonably well, then I'm in.

I think for every bike brand, we will be able to find someone with a horror story about a dealer or about a bike. That said, it is my experience that buying from a smaller, artisan manufacturer usually entails better customer service since you are closer to the bottom line decision maker than a mass marketer ever will be. There are exceptions of course.

Perhaps the best advice I give myself is to buy from a person or a company who has similar values to what you most cherish. Buying a bicycle from a low price leader like BikesDirect.com for example, and expecting the level of after-sales service like Bike Friday is foolish. Horses for courses, know thyself and buy accordingly :-)

Bought a Dahon Speed D7 off evanscycles.com this week and the bike arrived unable to unfold. The top of the locking pin was coming into contact with the forward frame and thereby making it impossible for the frame to align. Not entirely sure if the pin was placed upside down to begin with as the pin is flush on the under side and wouldn't have caused a problem if it had been the other way round. Not happy with Evan Cycles either as they claim to ensure that every bike is unboxed from the factory, examined, set-up and repackaged for dispatch. Everything else appeared done (tyres etc.) including the inclusion of Evan's multitools but there's no way this bike ever fitted together. The check sheet that should have been filled out by the staff was never signed off either. Box was in perfect condition as well. Very disappointing experience.

That is it in a nutshell. However the creaking is indicative of dry metal to metal contact so your Dahon's hinge may actually need to be taken apart and lubricated instead of just being tightened.