Through a post by Ghostmouse on WWWD?'s thread, I was lead to a certain eBay seller, sellandship.
Looking at their items, they have a lot of park surplus up for auction. The same kinds of things that Mouse Surplus and Surplus Kingdom used to sell.
Now, you can google this story: I believe Mouse Surplus was owned by a guy, but somehow it got taken away from him and the new owners didn't keep it up very well. Then, he spun-off and made Surplus Kingdom. Surplus Kingdom seems to have fallen off the face of the Earth, and Mouse Surplus doesn't look like it's selling much right now.
Could sellandship be related to Mouse Surplus in some way? Has anyone bought from them?
I bought from Mouse Surplus back in 2007, and I am the proud owner of a large leaf from a scene in WDW's Small World.