You can also use your mill to sharpen them, with better results as it is more controllable, using similar fixtures. Basically you are converting you mill into a precision grinder. No I have not personally tried it.
Fixtures for surface grinders (if you gave the grinder)
Denkle Clone (I have a Shars one as it uses 5c collets), still learning. Does Flutes and leading edge, center cut, can but still figuring that out.
True purpose built grinders.
Final true dedicated CNC grinder regrinders if you have the budget (ie win the lotto).
Important thing to remember HSS regular grinding wheels, Carbide, diamond wheels a must.