Cheap folders are often an exercise in frustration. I'd stay away from them unless you like to be frustrated.

Why? Lots of reasons. Main folding hinge develops lots of play. Parts are low-rent and needing constant adjustment. Squeaks and rattles galore. Difficulty folding and unfolding after only a few uses. Many times limited gear ranges, which means limited usefulness for most people. I could go on, but you get the idea.

In general with folders, you sacrifice many things on the altar of portability. I love my Brompton M3L for the uber-compact fold, but riding position is wonky, at least for me; gearing is limited; and it's expensive. The Bike Fridays are the best blend of portability and riding comfort for me. But they're not cheap either. It would be great if folks could test-drive a folder for a week. It would tell you almost everything you need to know before buying one. Would save many a purchase from that one deal-breaking issue that you didn't know you'd run into.