Energetic3D provide some of the best aftermarket beds available for any FDM 3D printer, both Textured and smooth surfaces are available. The textured beds are expertly powder coated and the Smooth beds are bubble-free.
We use the Energetic textured beds on our farm of MK3 printers so we can attest to the quality.
The Prusa MK3 and Prusa Mini beds do not have the magnetic base included due to the these printers already having the magnets built into the heat bed.
The square beds and custom sizes will have the magnetic base included making these beds an easy upgrade whether your printer has a magnetic base or not.