Besides Neill Miller's strops (I haven't had the pleasure yet but have full faith that they are high quality), I can highly recommend getting a Scrupleworks strop. They are handmade in Norway, and Torolf really knows his leather. I have a tanned cowhide strop which is actually supple enough for (careful) rolling when travelling, although I tend to use my smaller Dovo strop for that.
On that note, you can always hunt for a Dovo strop as well.