According to The Nappy Lady,
"REDUCED TO CLEAR. Following Bumgenius announcement that V5 is coming out shortly. We are reducing V4 to clear. When it's gone it's GONE!"
Looks like some are £10, some are £11.70.
I imagine other shops may well reduce them too.
Am I right in thinking these are quite popular? I'm wondering whether to buy some for my imminent arrival. I'm not too keen on the microfibre insert but I guess I can stuff with whatever I like.