I am using Bossbags on my bike since I got it. They are fairly easy to install and they are etachable. Volume is probably a little bigger than Harley bags and they are a little cheaper. Check them out at bossbags.com.
I got the Boss bags. around 700. very happy with them. i went a bought a 1 gal gas can , without the vent, was labeled "not for road vehicle use" well it fits very nicely in the bag with room for tools.
I have the HD leather bags (the ones with the HD nameplate) on my 2004 Black "B" Rod. 16,000 miles, and so far, so good. Spendy, but good. If you need to take them off, it only takes a couple of minutes. Not too bad, really. Beats hell out of bungieing a bag to that p-pad.
I recently bought a bag from Bags-connection.com. very nice bag. It cost me 289 Euro, and fit nicely on the back of my bike. Very durable. The only downfall was, I had to take it off everytime I wanted to fuel, which it only took a minute. I have a small backrest on my bike, which supported it from sliding backwards, though the straps around the shocks would have held it, and it provided a nice back rest too.