An option for adjustable bars are bushing bares that Bruce has. Possible Rich Daniels “barrel tester” on this site may have screw adjustable bars.
For the other accessories unfortunately, there is no resource for most of the items, as the sources are mostly out of business or retired. If Bruce does not have, the other options are Ebay, or as posted on the Bullseye Forum.
Fortunately the other items are all “extras” and not required to use the Star to reload.
Good,luck!