I just picked up a Sundeal F2 folding bike off eBay for about $200 from seller Crosslake Sales (d/b/a Random Bike Parts). They are surprisingly well built for the money. Mine was dated April 2015, so it's been sitting for a 3 years. The rubber on the Kenda tires were still good though. Hydroformed aluminum tubing. Good welds. Good paint (found a small scratch underneath), Acera derailleur and 8 speed Shimano cassette, Jagwire CEX cable housing, quick releases all over, mechanical disc brakes are all nice touches. I can see this selling for 2-3x as much if there was backed by a fancier label. It's nicer than any bike I've ever seen displayed at Walmart or Target which sometimes sell for more than this with crappier components. For reference, I own a full sized folder, Montague Paratrooper Pro ($1000), while it's a nice bike I'd buy this for 1/5 the price all day long. I owned a 20" Dahon briefly 15 years ago and it really felt like a toy bike and much less adjustable. I also tried the 16" Brompton at REI selling for $2k. Super twitchy steering. Aside from the slight flex in the adjustable stem (it's long since I like sitting upright) this feels like a full sized bike in every way. I can adjust 8" from the handlebar and about 14" from the seat (don't quote me.. I'm guessimating). Unlike Cat0020, I found the gearing perfect for me. I can see myself getting up to 20MPH. Mine clocked in just under 28lbs. About 28.5lbs after I swapped the seat for a wider one. The wheels, hubs, and calipers were no-name brand but they're perfectly adequate. The plastic folding pedals are serviceable but don't spin well, so that'll probably be next to go. I wish it had horizontal rear dropouts so I could easily convert this to a belt / IGH. This seems like a good candidate for a cheap folding electric hub bike conversion.
The package arrived from Advanced Sports Inc. who sells under Fuji, Kestral, Breezer, Oval, Phat, Tuesday, and SE brands. They're made by Ideal bikes based in Taiwan. They also have factories in China (where my Sundeal F2 was made), and Poland.
Highly recommended.
CAT0020, I'm in Brooklyn too. PM me., curious to see your bike.