I kind of think things should be left as is. Is it insulting to have your work (which is really only partially
your work) giving someone else a profit? Absolutely. However, if an eBay buyer
wants their collection to be covered that bad, they will make their way here. No eBay seller will ever be able to offer the full range of covers here for a price. As it is they have a handful of covers for different games. Collectors aren't stupid; they'll recognize that these games were never released in DVD cases. Some may buy, but, if they like the look of the case, they'll make their way here, find out they got ripped off and take it up with the seller on their own.
As for locking the covers unless you're an active member...that's kind of ridiculous. I've lurked for about 3 years now, and only recently registered, and we can all see the wild amount of activity my account has had.

There's not a whole lot here to put your two cents in on. It would probably bring in a flood of spam posts.
These guys likely aren't making much off of this anyways. DVD cases aren't wildly expensive, and they're charging shipping, but they're using the ink to print, the paper, they have to use gas to get these covers to the post office, it's likely they're losing money on the shipping materials as well. They're probably making a quarter at most. If they want to go through all that effort for a quarter, then oh well.