Nose strut rebuilt / replace options?

My mechanic has suggested that I have a well worn nose strut (single fork or a 415C) and worn axle all contributing to my shimmy.

Are they any outfits that rebuild these or that sell them already rebuilt? Reading online it seems one of the suggestions to fix shimmy was to go to a dual fork. Is that the right path or will servicing the single fork usually work? Any idea what it costs to go to the dual fork?

Thx