>>3638310You can get decent focal lengths for APS-C or M43 in the range betwee 300mm and 1200mm (480 mm and 1920 mm equivalent) rather cheap as well.
Usualy no more than 50€, often cheaper.
However these tend to not be telephoto lenses but actual long focal length ones, manual focus and realy slow.
Pic related, shot with a lens of unknown exact focal length somewhere in the 250-300 mm range and cropped a lot.