I've been using the Zéfal RX 300 pump for several years now. It was not very expensive (approx. €18 at the time) but it's very reliable. The site claims it can pump up to 5 bars but I've never checked this. I take it with all my bikes (in fact, I always carry it in a bar bag in the folder, inside a pannier in the tourer, in it´s own carrier in the MTB...) I've used it only a few times away from home, and it was able to pump a rear tyre to meet the demands of a loaded bike.
Roberto