Sounds like low supply and really high, unexpected, demand for the Holidays.
My guess is that you hit the nail on the head. DEMAND being the big word here. Kept checking at 2 local Walmarts before Christmas and I would just miss it every time. I refused to pay $600+ for a ipad. I researched all tablets near and far on the internet and retail stores nearby between $100-$200. By far this was the best bang for the buck. Was told at Brandsmart that some of their below $200 android tablets were bad about freezing up. Vizio has not let me down yet!!!