Last time I checked, The Shootist in St Albert had one in stock. Can't say if its still there or not -
www.shootist.ab.ca. The inventory is online.
I think between the 338 win mag and the 338 Lapua, the 338 RUM got casted out. Its fairly cheap to shoot factory ammo in a 338 win mag, and if you into re-loading/longer ranges, then most people will go for the lapua. 338 RUM kinda fell in between and lost the popularity battle I guess. Its still a great calibre though!