Tesco Bradford have these Owl USB Connectors for only £2.62
They allow your PC to receive signals from your Owl Energy Monitor.
Graphically view/plot your energy usage
I bought three, there was one left over.
I don't know if it is nation wide or not.
Forgot to say.. The shelf end label said £10.49 (Reduced from £19.99), but it scanned at £2.62
That's why I went back for two more.