The only thing that I would caution you on as far as the non-HD ones- ESPECIALLY if buying online- is to look VERY closely at the gauge that tells you how many pounds you are putting in. I am speaking from experience, and I literally just walked in my door coming from buying one at the HD shop. I went to probably 10 different bicycle shops, and looked all over the web, and the smallest increments that I could find the pressure gauges on these pumps was 5 pound increments. The HD air-suspension shocks are VERY sensitive, and 1 or 2 pounds makes a HUGE difference. I couldn't find a hand pump in 1-pound increments ANYWHERE, so I went ahead and bought the HD one. It's hard to tell from the online pics what pounds the gauges measure.
Keep your eyes open for that little gotcha- and good luck!