I got a pair of pouches and a box from Amazon as I wanted one to put the spare key in that sits in a drawer upstairs, the other I keep with me to use when out of the car(so nobody can sneaky it sat at a table near me in a cafe etc) and the box I use to throw it in as soon as I come through the door, that way I never forget to do it before I go to bed.
Regarding specific ones I just did a bit of shopping around and read reviews and asked a few questions, all 3 cost me a total of £28