Here's my 0.02
Asking for technical advice from the list, getting it, and turning
around and selling a fixed item, to... eBay, is Most Rude.
Letting the people on the list save time on searches by making
small inobtrusive FA announcements: Offers a slight benefit.
Offering things to the list first, waiting for responses and then
resorting to eBay is Most Generous.
John A.
looks like a balancing act. see: "Ethics"