It appears that the original Watchmen series is just 99 cents a pop on ComiXology. Might be worth the trip.
Although, you can get similar prices on Amazon marketplace for the print version.
They have also got the first issues of the Before Watchmen series for the same price on ComiXology.
Which is handy as today's the day a bunch of Before Watchmen books hit the shelves in hardcover.
ComiXology are also running a Brandon Graham sale right now too, with King City, Multiple Warheads and Prophet reduced right down.