VMWare Fusion 3.1 is currently £27.99. The nearest competing price I can see (using Invisible Hand) is £42.41 at LambdaTek (no idea what their postage is). Fusion has an RRP of £64.99 and is usually found anywhere from £42 to £60.
Note - VMWare Fusion is for Mac OS X only.
Additional note - If you want similar functionality but for free, you could check out http://www.virtualbox.org/