@ WiFi. Channel 3 is also a good place to announce bots with no GC or EMU. It is trade related after all!!
I don't think this would be appropriate. #jc 3 isn't for calling someone out - i.e. if you think someone is scamming you or charging outrageous prices or doesn't have as much money as they thought they did. In similar fashion, it's not appropriate to call bots out.
RE: Topic as a whole
What do you do when a store is having a special and they run out before you can buy one? Do you stop shopping there? Even when the store advertises "While supplies last"?
And just like real life stores aren't open 24/7 in most cases... most players aren't on 24/7 and active. So a bot could easily fill up while someone is at work or asleep. And even if they are on, they may not be monitoring gc levels or EMU levels 100% of the time.
Bots are not a perfect solution for many reasons. Perhaps leave a simple mercator message to the owner that you had to go elsewhere because of lack of gold or EMU. It doesn't have to be "And I'll never shop here again!!!~!111one!!!". But it would help to make him/her aware of the issue.