The iPad 2, Amazon Kindle, Transformer Prime, or Galaxy Tab might be the best tablets available right now, but they aren't cheap by any stretch. Sprint's new ZTE Optik is a pretty decent spec-ed tablet that only costs 100 bucks and has 3G.
Your $100 buys you a 7-inch tablet with a 1280x800 resolution display, dual-core 1.2GHz processor, 1GB of RAM, 16GB of internal storage (micro SD card included, too), GPS, Wi-Fi (b/g...no n), Bluetooth 2.1+EDR, 4,000 mAh battery and stereo speakers.
There's two cameras on this guy as well. A two-megapixel camera on the front and a five-megapixel cam on the back.
Operating system looks to be Android 3.2 Honeycomb (no Ice Cream Sandwich here)
For $100 you'll probably only use this to watch LOLcatz, tweet, stalk people on Facebook and read DVICE all day long anyway.
You can have at one on February 5 with a one-year contract. Plans will cost a minimum of $20 for 1GB of data on Sprint. You can also buy the Optik for $350 without contract.