So, say some dashing rogue with an angry black star in a purple circle for an avatar visits the site and asks a question along the lines of:
"Hey, where can I get cheap, quality [iso graph paper/regular graph paper/d4/d8/d10/d20/d100/d7/fudge dice/human slaves/dry ice (for atmosphere)/whatever else]?"
On one hand, props and atmosphere questions are on-topic, and some of these may fall under that umbrella (i.e. the dry ice thing). On the other hand, finding art, game-recommendations, and snacks have all been said to be off-topic, not to mention this kind of question could very easily draw solicitation, which isn't really something you want outside of SO. When that dashing rogue (who absolutely doesn't live in his mother's basement) had this question before, he played it safe and ventured into chat (his biceps gleaming in the moonlight, completely unobscured by cheeto-induced and -dusted flab).
So, again, would asking for places to find quality supplies be on-topic?