It's against the community rules for any of us to suggest any selling sites other than eBay, and I wouldn't really have any brilliant ideas even if we could.
I am a paper crafter, and I look on eBay for discontinued paperpatterns, die cuts, etc., because I can't get them on a "regular" retail scrapbooking site or in a craft store. I guess I'd start with any discontinued Graphic 45, Bo Bunny, Echo Park, Carta Bella, Stamperia, etc., and make sure you market your listings with the right keywords, etc. I think the holiday items (especially Halloween and Christmas) go over pretty well any time of year, since crafters try to stay ahead of the seasons/holidays.
The only thing I might sell in lots would be cardstock or inexpensive single-sheet paper from places like Hobby Lobby, JoAnn or Michael's--paper you can get really cheap when those stores have deeply discounted sales. You kind of have to ask yourself whether you want to make money or you just want to get rid of the items.
I'd wait for last to offer those "current" items (stamps or whatever) that people can go to their local store and buy right now--without having to pay the shipping fee to an online seller--not just eBay sellers, but many of the online retailers charge shipping. Why would they pay shipping when they can pop over to their local JoAnn? Or order from a regional or national retailer with free shipping over $XX?
As I said, we cannot recommend alternative venues on which to sell items, but if you would ever decide you had some things to donate, please contact your local arts council (ours has a great kids' program) or your local schools, daycares (particularly low-income, Head Start-type programs) or even nursing homes or senior centers. Those kinds of not-for-profit organizations would be thrilled with those kinds of supplies. Maybe you could even teach a class or two?
