Chargers are pretty cheap. I'd error on the side of caution and get one made for, or meeting the specs, for the Vtab. I just bought this one on ebay:
eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices
That charger is only rated at 1 amp, you really should get one that is rated at 2 amps.
Sounds like a good idea. The EBAY ad says it is made for the Vizio Vtab, but you never know. Do you have a link to a 2 amp model?