I got
this (though in blue) for almost free with the ink cartridge coupons. Still looking almost brand new & I've been loading it with books all semester. The 5 year warranty isn't bad, either. It seems very durable, and I have no reason to believe it won't last me for quite a few years.
Edit: This is probably true of all messenger bags, but I like using the handle & you always have to buckle it up just right first. You get pretty quick, but still something to keep in mind. The buckle is adjustable, but has a tendency to slip if you don't run the strap through it twice.