Last night I ordered a Logitech keyboard cover for my iPad mini from Amazon. Logitech is widely thought to make the best keyboard covers for iPads, and this one is 75% off through a third party seller (Tiger Direct): $19 instead of $79. Even with $4 shipping, I came away under $24, thanks to TD not charging sales tax in Indiana (Amazon does).
http://www.amazon.com/dp/B00CR61RW0/...332200_TE_item
Here's a pretty good review of it. It's not fond of the size (constrained by the iPad's size, obviously) or the placement/size of the shift keys, but otherwise it's very positive: