Think they're talking about 'special' deals, as opposed to proper availability at mainstream retailers.
Yes there are special deals, but a couple of week ago the 3900 for £320 now it linked to a 3800x not sure if at the time it was linked to 3900 or 3800x at the time.
But there were a few at £340 around 2 weeks ago after the prices of the 5*** were shown it looks like quite a few Cpu's got a price hike.