Some tips on having a good experience purchasing used iPads on eBay:
- Find an experienced, highly rated seller
- Look for a reasonable return policy
- Account for shipping costs
- Purchase from US-based sellers
- Avoid any iPad with a replaced screen or digitizer
- Avoid screen cracks that have propagated into the viewable screen. Cracks on corners are usually fine and typically not visible with an inexpensive case.
- Case scratches don't matter. Case dents should be avoided as the internal components can be damaged.
- Ask for a screen shot of the serial number of the unit before purchasing. The serial number is located in Settings>>About. Confirm you've received the correct device.
- The device should be fully unlocked with respect to iTunes and iCloud.
- Don't pay a large premium for an iPad with built in cellular. Though this feature is convenient, you can get the same functionality using your cellphone as a hot-spot when Wifi at the event is unreliable or unavailable. It's easy to turn a modern cellphone into a hot-spot.
Here's a link to a comparison of all the iPads (except the Pro versions). Click here.