Last TGS and this TGS I used
ZenMarket to get the merch sold through KT Spot. Last year I paid a lot for shipping but everything arrived in top shape. This year I'll use them again and can report how things arrive in this thread.
Autographed signs can only be acquired through Twitter contests. I was lucky enough to get one from Saori Oonishi from a Kokoro fan that won a contest years back.
That admin is correct. Even if Fandom is more lax in what they allow compared to Wikipedia, an encyclopedia should be a collection of verifiable info, not speculation. For that stuff it is better to use a website like TV Tropes.