Lathes

Is a good place to start, they also have a for sale section.

Used lathes is a bit of an odd market, secondhand hobby size machines often go for more than industrial machines because it is such a pain in the bottom moving 2 tons of cast iron.

smart & brown lathes are some of the best ever made but 50 years of abuse will wreck any machine, if you are planning to do a conversion to cnc that will be less of an issue as you can retrofit modern rails onto it.

Smart and Brown L4 Lever Operated Collet Lathe | eBay

Smart and Brown. "L" Collet Lathe Very Light Use. | eBay

USED LATHE (SMART AND BROWN). | eBay

Smart & Brown 1024 Toolroom Lathe | eBay


I've had an ebay search setup for a few months for 'smart brown lathe' and I've noticed that a lot of these machines get re listed over and over again, just not that much demand for them.

There are also auction sites where cheap lathes pop up on from time to time.

If you are going to do a conversion you could always go the whole nine yards and just build one from scratch:

Scratch built CNC Slantbed Lathe - finished. - YouTube