As I understand it the problem with Super Takumar 50/1.4s only affects the earliest model of the lens. If you find one of those cheaply then you'll be able to sell it on for enough to cover a later 50/1.4 and still make a profit! There's plenty of information online about identifying them.

As for small, there's an Industar 50mm f3.5 pancake in screw mount but it's completely manual. Mine doesn't even have click stops on the aperture setting, let alone a preset or auto mechanism to stop it down.

Would 35mm be any use to you? The Super Takumar 35/3.5 is very small and very lovely, it's a bit slow but for daylight shooting with 200ASA film it'll be fine, and that's generally what I put in a camera I plan to carry around on the offchance that something will happen in front of it.