If you are in N. Amercia:
Apple sells these at a reduced price but with a full warrantly and freshened up, to wit:
Apple Certified Refurbished
We test and certify all Apple refurbished products and include a 1-year warranty.
All refurbished iPad models also include a brand new battery and outer shell.
Our iPad 2 is a refurb we bought last year and it works and looks great.
iPads are in such demand that the old term caveat emptor comes to play. There are people out there who will rip you off. That's why we buy refurbs directly from Apple.
BTW: Apple does not post in these forums. We are all end-users like you so can't speak to Apple's pricing other than what we see posted.
Here's some sites that buy iPads, so I assume they also sell them if you want to buy used. Don't buy an iPad 1.
How to Sell Your Old iPad http://tinyurl.com/85d69lk
Other sources to sell.
eBay Instant Sell http://instantsale.ebay.com/?search=ipad
Sell and Recycle Used Electronics - Gazelle http://www.gazelle.com/
For instant gratification in selling a used iPhone or iPad, Gazelle’s Gadget Trader, an iOS app, is tough to beat. In seconds it detects the device and reveals how much it is worth in good condition. Tap the Sell This Phone to Gazelle button and the deed is done.
Sell Electronics for Cash - Next Worth http://www.nextworth.com/
Buy My Tronics http://www.buymytronics.com/
Sell Your iPad http://www.sellyourmac.com/mac-product-guides/ipad.html
But, you need to determine which model to buy.
16GB vs 32GB vs 64GB: Which new iPad storage capacity should you get?
How much content will fit on my iPod or iPhone?
iPad Mini vs. iPad 2 vs. iPad 4: Which iPad Should You Buy?