For my project, I need a rotary encoder. The first requirement for it is to be cheap, and I am not sure how to even start looking for them. The RLS magnetic encoders seem cool, but they are a bit more expensive than I would expect.

The supported speed should be 5000 rpm, which should not be a problem for any encoder.

In terms of resolution, it should best be a sine/cosine output, 256 or so cycles. It could be 100 or 1000; it doesn't matter much.

Unfortunately, I am not even sure which technology is the cheapest nowadays.