Do any companies sell just a frame? Or would I have to go used? I was sort of interested in getting a folder, but much prefer to build up my own ride. Thanks.

you can get a Swift frameset for $499 plus shipping.
https://www.xootr.com/swift-frame-set.html

The Xootr Swift has a frame set, i've seen Airnimal frame sets available in the past (and they may still be, but I don't pay a lot of attention to Airnimal), and while I don't believe that Bike Friday will sell you a lone frame set, you can send your parts in to their shop and they'll build them onto a bike for you. They also do custom order out of the gate, in case you don't have the parts.

Just as a side note, the Xootr Swift is easily the cheapest of them for a frame set, and its frame alone costs more than many new decent folders do. Folder framesets are not cheap.

A popular bike to tinker and mod with, and customize into your own, is the Raleigh Twenty.

Ouch, $500 for a frame? Abneycat, I think you might be right in sourcing a Raleigh Twenty for cheaper and modding it. Thanks for the advice guys.

Calhoun Cycle sells Airnimal Joey and Chameleon frame kits.

It may be the way to go if you're looking for a custom project on a budget. The Twenty is a good frame and has a very renowned ride to it, but it is not the lightest nor the most modern. You can find more information about projects using this bike online if you are interested, as there are many fan sites. Sheldon Brown's site has detailed information on the subject:

https://sheldonbrown.org/raleigh-twenty.html

Contrastingly, the Xootr Swift frame for instance is much more expensive to buy than an old Raleigh, but the frame will be new, lighter, and it will be user friendly regarding using modern, mainstream components as opposed to the Twenty, which requires some hunting and sourcing and effort in order to customize beyond basics.

I think it's worth noting that there are lots of different types of folders, and some serve a purpose better than others. A Bike Friday for instance, is a very high performance folding bicycle - but for pure size and convenience of folding, it falls far behind most other choices. A Raleigh Twenty is a great choice if you enjoy vintage bikes and don't mind the folding size, but a Twenty is not a great bicycle from a pure folding perspective either.

What are you planning on using your folder for? It might help narrow down which models would be better.

My Bike Friday Tikit with hyperfold folds very quickly and easily, without having to turn any knobs or undoing any quick releases. It locks together when folded and has a built in handle for rolling it on its front wheel. It's one of the very few folders on the market that require absolutely no adjustments when unfolding. And it fits very nicely in my small trunk.

I happen to know all about the Tikit, having retailed Bike Friday including the Hyperfold Tikit, and i'm a Pocket Llama owner. The Tikit is more convenient than their pocket bikes, however the Tikit is still a very large package for a 16" class bicycle. Bike Friday offers performance more than package size. And the Tikit is a nice ride, but it does not fully live up to the ride of its bigger BF brethren. If it fits in your trunk, great. My Llama has yet to fail to fit in a trunk, but it would be a pain to get onto a bus, likewise, there are many people out there who need the size offered by a Dahon Curve or even a Brompton.

I was simply discussing the differences in size and performance, and that all of these folders vary differently on the spectrum, and that should be considered when looking for a folding frame set.

Custom on a budget is definitely what I'm going for. I had initially figured if a folder with gears can sell for 400$ I could build up an SS with what I want for a good deal less. I'm not looking for super-duper small folding size because I know they're going to be relatively small no matter what. I'd use it mostly as an around-town ride, and the folding ability would be good for trips, when I happen to take them.

How about just getting a Dahon Boardwalk? It's inexpensive and only has one speed.

--sam

I do have a Dahon Curve frame .... new ,,, no fork or anything else, just the frame in red .
I bought it from Dahon as a replacement frame for a customer, and the customer never picked it up .... I sell it for 150 bucks

thor