just got the M.Zuiko 14-42mm f/3.5-5.6 EZ pancake lens a few hours ago from eBay that I referred to here. In this case, it seems I lucked out with a bargain price and no compromise apart from lack of warranty.
The only other lens I ever bought online was not used but possibly a display or demo model, because it was sold in “New” condition at half retail price - a Tamron AF 18-200mm f/3.5-6.3 Di II VC (for Nikon F-mount). That was through amazon.