If you want a powerful, high-resolution tablet from a reputable manufacturer, you're going to have to pay for it. If you'd like to pay considerably less, you should check out the current Adorama listing for ASUS' flagship Transformer Pad. The Infinity TF701T is on sale for $349.99, a full $100 off of the retail price. It's also $50 below Amazon's price.
The TF701T is the latest and greatest tablet in the line, combining a speedy Tegra 4 processor, 2GB of RAM, and a 2560x1600 resolution to make a compellingly capable tablet.