Thanks Ted. I was just thinking the same thing.
I wanted a new helmet for a road trip to the Stratford Vinduro (be there or be square.......
) and picked out what I thought I wanted online.
When I got to the shop today, that particular helmet didn't fit my oddball head well at all.
In the end, I spent more than I planned, but got a top line helmet (Shoei) that is seriously comfortable, the vents actually work and it's quieter without earplugs than my old one was with earplugs, all for 40 buck LESS than the cheapest one of that model on eBay.
If I'd bought online, I would have been well out of pocket today.
Not always the case, but there's no going back if you get it wrong.