Today it is the GWR King
http://store.steampowered.com/app/65236£4.80
€5.74
$7.63
$ & € prices done via Xe.com say may be cheaper.
For those intrested about the locomotive heres the wiki page
http://en.wikipedia.org/wiki/GWR_6000_ClassThe locomotive is very good, as i got it in the Christmas sounds. But the sounds are very disapointing as to me (Lived/ Lives in an ex GWR area) are very wrong, as they use the sounds from the Hall Locomotive that was made, and both locomotives sound very difference.
Gladly a sound pack on uktrainsim.com that gives them more realistic sounds
Chris