I would probably post up at a local honda dealer for maybe some who was unlucky and bent or messed up their rear wheel... Could be a good deal for them, but even $300 is a bit high i think for one wanting a black wheel. One can get their stock wheel powdercoated for around $80 - $100. Just my thoughts... A bad deal to one could always be a good deal for another!
I think $300 shipped is a fair price, your market is someone who bent a rim for whatever reason, or someone who bent a chromed rim and has to replace, or someone who sent theirs in to be chromed and found out the rim is bad. or someone in a warm climate who wants to widen it without any downtime. Good Luck.