Thanks a bunch! I think I just order the stuff and hope it fits. After all, as you correctly deduced, I am currently stationed in Malaysia and the stuff is incredibly cheap here, headset 5us, fork 5us etc. just want to take the opportunity to take as much of the old stuff laying around on the shelf and use it for this bike. Will be a wild mix…the one thing which is a bit of head scratcher is the chain line. With a single speed this needs to be right.
I understand. But what Fentuz and I both said is good advice. Let me put it another way. Versus a new bike, perhaps you save 50% on cost; 50% on USD$1000 is a lot different than 50% on $300. If you can get a complete folding bike as cheaply as parts there, go for that, it will be far superior. However, if you start with a quality frame like an FnHon and build up the bike, it will be even better as you can choose to use better quality parts. Just make sure things like "Shimano" parts are genuine, as many fakes are being sold on Alixxx and other sites. Buy through a reputable dealer of those brand parts.
I would start first by deciding what size tires you desire, both diameter and width, then what style folding on the frame, and what style brakes, then correct size to fit you, and obtain a frame and build up from there.
Both Ron Damon, and a member called ChiapasFixed, started great threads on buildup of multiple folding bikes, the latter did 4 different ones for a family tour of southeast Asia:
Folders for Family Fun