Just to play Devil's Advocate and give the alternative view......
1) Diamond 220 speakers aren't £99 new everywhere. There are a few retailers still listing at £179, or close to the launch rrp of £199
2) Diamond 220 were available in three finishes: Black, walnut, white. AFAICT, the £99 deal is limited to just black, and by the look of it from just one retailer who has bought up the remaining stock on an end-of-range deal. If you want another colour option then you're going to pay a premium, and there are lots of Ebay 'Buy-it-now' listings in the £199 - £279 range, so that distorts buyer's perception
3) The Diamond 11.1 takes over from the Diamond 220, but it's £280/pr and that that price it faces stiffer competition
My advice to any would-be purchasers is to grab the deal at £99. It's cheap.... Really cheap. Yes, if you wait around long enough then some cheaper used examples might become available. Maybe you'll save another £20 or £30 on something used. My view is that at the £99 for a new pair with warranty then would I trade the hassle of a private sale and no warranty plus the risk of shipping for the cost of a couple of big pizzas and some beer. The answer is no. Life's too short. Get the £99 deal and move on with the project.