It would help to see pics to be sure, but unless the base has been messed up you should be able to bolt a stoker assembly onto studs that are already there. You'll need an auger and pipe with that, and check the base on the opposite side from where the stoker would mount to make sure there's an opening with a collar for the auger pipe to pass through. If it was set up for the burner to fire into the base, you might want to remove any insulation/combustion chamber material that was added to the base. If there's no timer you'll need one.
$ for the parts you'll need depend upon whether you want used, refurbed or a dealer unit. If you give us a hint where you are we could make suggestions of possible sources.