Posted: 01/05/2016 at 13:36
Aren't there something like 5000 volunteers at London? No idea if they all get a medal, but if they do then even though there are fewer official medals overall, there may be a lot more people prepared to sell one. There are usually more 'official' medals than finisher medals for sale on ebay.
Pretty sure we were offered officials medals for helping on the water station at London. I also have one for helping at the mini marathon.