A few suggestions for fixing/improving the accessories:

a) While keeping the cost of the Silver Key the same:
--Reduce the randomness of the lockboxes. Have some indication as to what is in the lockbox, such as helmet/armor or color. No need to give away the "rarity" as this would deter players from opening boxes that may contain barrel bellies and the like.

AND/OR (emphasis on the "or", as I think this is the most important fix)

--Make the accessories only bound to the owner once worn and not destroyed when removed. This fixes the problem of letting players keep their hard-bought accessories when they upgrade their armor or want to change their costume.

OR

b) Reduce the cost of the silver key:
--Keep everything the same as it is.

OR

--Separate boxes into common and rare and have a different key cost for each box. That way, the "poorer" players can have a choice as to if they want to take a chance at a rarer box or stick with a cheaper box.

~~~~Below are my own thoughts:
I can foresee more problems with the last suggestion than with the other ones (i.e. nobody opening the common boxes, rare boxes going for much higher in the AH because of the known rareness, as opposed to all boxes going for fairly cheap right now because of the risk of The Belly).

My personal preference would be option (a). I have no problem with Three Rings charging what they charge, given that I can keep the item that I bought/traded for and have it not be destroyed when I want to put it on something else. If I'm the one buying the key, I would preferably like to know if the color would match my character, as well. I don't see any problem with putting the color on the box as I could just trade the box to someone with a color that I want, even if I still don't know what's inside.

I understand that this is basically the SK version of the grab bag, and I'm fine with that. Grab bags are fun and hilarious in real life because you're bound to get something weird or something awesome; unless if you have high expectations you'll always get some enjoyment out of them. However, paying and free players alike are having trouble with this grab bag system because it's TOO random and can get to be very expensive, which is why I think either of my proposed options could work and still keep OOO earning and the players happy.