Check out Texas Side Cars. They list the VT600 on their application chart. Price is approx $3500.00. You may also want to check Velorex, TAmpa, FL.
They list 4 models and their prices range from $2899.00 to $3999.00.
Trike Conversion Kits range from $2495.00 to in excess of $10,000.00 depending on the manufacturer.
thought i'd share these pictures....
i had been thinking about a sidecar myself and had never seen one on a shadow before and to my surprise i was walking out of a bank and saw the unmistakable lines of a shadow aero drive by with a sidecar so of course i chased it down.
not sure if the gentleman is on the forum but he was nice enough to stop and chat about his setup and let me take pictures.
i believe it was a 98 aero 1100 with a 1930s era bmw sidecar
the lines of the sidecar especially from behind flowed so nicely with the aero. aside from some serious mcguyvering to install the sidecar i don't have much more info