The cost of the repairs you are proposing are more than the shipping charges. If you planned on changing the bike's color or modifying it cosmetically when you bought it, then the scratches are academic (other than the fact that the seller didn't disclose them) because they would be addressed in the re-do.
I would file a complaint and let the process work itself. If you don't get resolution to your satisfaction, either make your cosmetic changes, ride it 'as is' or sell it. This is one of the perils of doing business with sight unseen purchases and trusting the seller. I would not recommend returning the bike unless you are credited first. Best not get burned a second time. If you have to pay shipping charges, that is the cost of the lesson. As a general rule, the best you can expect from the resolution process is a reimbursement for what you paid unless the seller is willing to be ethical.
Personally, I would let the resolution process work itself out. If there is no offer to resolve the shipping costs that meet your satisfaction, I would just ride the bike. It will get damaged like that sooner or later if you ride it enough. Then use the return shipping charges to customize it and put the experience behind you as a lesson learned.
Capiche?