How about a report/manual all about how to source spares for Japanese cars?
The OEM parts can be incredibly expensive, but there are always speciality shops which sell reconditioned or alternative manufacturer parts.
Or perhaps an updatable ebook with all the swapmeets and events held nationwide for Japanese sports car enthusiasts. If it is updated monthly, it could even generated an ongoing income.
Just 2 quick thoughts that might help.
Martin Avis
BizE-zine: Success strategies that really work.