Sounds a bit like a warmed-over rerun of a rumour that was doing the rounds a few months ago - there was a PQ asking about plans to lease 4 P8s.
IIRC the lease-then-buy arrangement for the first 4 C17s turned out to be quite a pricey way of going about things. But at least we ended up with something decent to show for it, unlike the squillions p*ssed up the wall on MRA4 and the Harrier upgrade...