I hated trying to type into the search box, using the up/down left/right of the basic Firestick control, so just before Christmas and soon after getting the Firestick, I decided I must have some sort of Bluetooth ASCII keyboard. I ordered a tiny one, the same size as an Iphone from HK, that arrived on Monday. It was tiny and delicate and the KB had burst open in the post. Reasembled, it wouldn't work at all, so I have started a dispute with the seller over that one and ordered another style from a UK seller, which I then quickly cancelled because the seller seemed to confuse 2.4GHz with Bluetooth in the description - it was actually a 2.4Ghz. I then ordered a third one, which arrived this morning and it works with all that I have tried it with, including the Firestick.
This one -
http://www.ebay.co.uk/itm/111988837965
It is a touch smaller than a standard keyboard, without the numeric keypad, and feels well made.