I've seen this implemented on a few servers and think it would be nice to have a time limit on @at and vending, after which the vendor will be logged and must set up shop again.. say 48 hours?
I think this would really help the economy since people will be forced to reset shop and be more motivated to sell their junk fast rather than force their OP'ed stuff down everyone's throats.
Also it would make it extremely annoying to have 10 venders per person sitting in prontera vending crap no wants.
The struggle to free myself of restraints becomes my very shackles. - Meshuggah