Haha, yes, they go to Ebay
As soon as one size sells out it appears on ebay almost within the hour at £250 tops (particularly coats). There is actually a faux fur car coat in Topshop at the moment, which is also on Ebay for £250 - £300. The size of the Ebay item is still in stock at Topshop, so it makes no sense whatsoever. Who really buys this stuff?
I'm not sure how it works, but perhaps the smaller and larger sizes sell out fast because they don't stock as many as the more standard sizes, ie, 10, 12, etc.
Haha, you know that I've been checking there to see if they have them but I haven't come across them yet. I did once find a tunic there that I really wanted but didn't buy and it turned up about 3 or 4 months later, so I'm holding out hope!