Apple has lowered its prices on its refurbished iPad Wi-Fi units while adding 3G offerings. Compared to the prior discount of $50 off retail for Wi-Fi models, the 16GB model is now $429, or $70 lower than retail units, while the 32GB and 64GB Wi-Fi models have seen their prices slashed to $499 and $599, respectively, a discount of $100 off retail. The refurbished Wi-Fi + 3G models are discounted $50 off of retail bringing their pricing to $579-$779.…