I end up selling the ones I don't use as often, because my space is limited as is my budget for LV. I have done it on ebay, which is difficult, because of poeple selling fakes and certainly overly cautious aren't always the most polite. You would be surprised. There are people who are selling assistants of LV, mostly MY Poupette sellers. No, I am not a myPoupette seller, so no self-promotion here. Some people sell to trade up. Ha ha.
You could have someone sell on your behalf, if you want to sell. Or, if you're a collector and have lots of room, then keep them. It all depends.