Hey, I'm online right now for the next two hours or so. I'm in the GMT+1 time zone. A "void" is where your villagers go after they move out. That means: if a villager moves out, and you visit someone else who has 9 or fewer villagers, then this villager will most likely move into that other town. It is, however, possible to clear the void, if you visit someone with 10 villagers. Then all the villagers who have moved out will be deleted from the "void".
I have 9 villagers at the moment and I'm waiting for a certain villager to move in. But if I have a random villager from someones void moving in, then this other villager can't come anymore, because you can only hold 10 villagers in total. I hope that wasn't too confusing.
That being said - if you still want to sell, and if you have a clear void (i.e. if you've visited a few people's towns after the last move-out, or one town with 10 villagers), you are welcome to drop by. Just send me a pm, so I can open my gates. If your void isn't clear, I would kindly ask you to find someone with 10 villagers and visit them first.
Edig: I completely forgot - it's 10 to 11 here; Re-Tail closes in 10 minutes... :-/