The question of whether to post or not depends on how comfortable the individual is to pack something securely enough to last the trip to its new owner and not burst into flames when it gets there.
I've posted so much stuff that I've lost count of it all and its second nature now. I could probably, at a push pack my 8x10" (original box was used to post a trace 1x15") but would rather deliver within reason as the cheapest quote i can find is £72. At 25p a mile, you could live as far away as 140 miles away from me before it became cheaper to post.
Then again, as people have said previously, not everyone has a car, the time or the will to post something large.
I think its a good idea to list where you are in your thread or at the very least at the beginning of your listing to avoid the type of GAS where you are unable to act on it (whether that's good or bad)
man, I'm really beginning to wander now. nurse? nurse?