Auction for the in-game item codes mentioned numerous times above ended at
26,500 yen!
So, enlight of the first seller who more than successfully sold off the rights to his concert ticket bonus in-game item codes, another seller is now offering them, and has additional pictures of what I assume are additional in-game exclusives the other seller failed to detail.
http://page16.auctions.yahoo.co.jp/jp/auction/u45434406Yes, there were official PSO mangas released pertaining to DC PSO, and later at least one based on Episodes 1&2. If the old Sonic Team PSO website were still online I would link you to the official merchandise page which detailed them.
EDIT:Just spotted this!
PSO 10th Anniversary PSP - Had no idea this even existed!
http://page8.auctions.yahoo.co.jp/jp/auction/h173324522