There are a number of seller of the Air 3G that will sell you bundled keyboards for your tablet. 99% of them are absolute rubbish, with poor key travel and keys that have no spaces between them making typing very awkward.
Logitech have the solution, it’s a tablet keyboard with its own case that can double as a stand for your X98 Air 3G. The key travel and feedback is great and it’s a full sized keyboard.
It’s not expensive either, they retail for $69 usd. But I found them $29 here: http://goo.gl/L001W7