I did a 9A to 9. It cost around $2k (new engine mount, main gear legs and tailwheel assembly) and took 4 days. A day to put the tailwheel in, 2 days to swap engine mount, reroute brake lines etc and a day to modify the spats.
Depending upon the condition of your existing gear, I might be interested in your engine mount and front landing gear. I'd have to test the mount for cracks and the front gear has to be the latest version.
Having just finished installing my tailwheel and cabin gussets (where the main gear legs would be attached in a tri grea) I can say that it would be a piece of cake to convert a -9 back and forth as far as the fuselage mod is concerned. The engine mount maybe another issue.