Equal if not greater protection, larger volume before cleaning, and nearly a sixth the price is the Sawyer SP135.

Granted, Moontrail (Sawyer SP135 for$79.00) is the cheapest site I've seen that I know to be reliable (a couple of friends ordered the SP135 from them after a person in these forums did a post on it.

Sawyer SP135:7/6/5.5 log, 3000 gallons, Cleanable, $79.00
Lifesaver Bottle: 6/6/4 log, 1585 gallons, Expires, $460.00 (high capacity model)