I just noticed this on the Apple website:
https://www.apple.com/ipad/trade-up/
They're offering $55 on a 16 GB iPad 2 or $80 on a 32 GB iPad 3. I still support these old iPad models, but I see more tech support issues with these models than with newer models, especially when they are maxed out at iOS 9. So if you're still using an old iPad, this could be a great time to upgrade to the latest iPad 9.7", which starts at $329.
BTW, those trade-in prices are a bit lower than you could get selling the old iPad yourself (looking at current eBay prices), but it would be more convenient.