VGC has the Vita at ~3k/week, but it's off by >50%. (19.5/4 = 4.9k /week)
Saving for big releases, the Vita tends to slightly edge the Wii U on VGC, this might indicate the difference is a little bigger if we assume the estimation is similarly off in other Western territories. This is pretty questionable however. (Wish we'd get sold through and sold-in numbers from the Tokyo cowards.)