Buy three! I've ended up having to buy new chargers for my last two laptops, and since it was an emergency when their chargers died, I had to suck it up and pay $80 each for the replacements. Having bought, now, 6 (iGo) chargers from Woot, I have chargers in my office, on my desk at home, in my backpack, and in the laptop bag I carry to classes, plus an extra in the closet and one I gave to my hubs when his died. It's a significant quality-of-life improvement not to have to remember to carry my charger with me from home to work and back (more than once, in the old days, I either wasn't able to use my computer at home because I left my charger at work, or had to dash home from work in the middle of the day to get it.)
If I didn't already have a charger everywhere I can imagine needing one, I'd be all over this!