I agree and disagree.

If your friend only wants to read The Watchmen then the Trade Paperback is the way to go. If he's a collector the individual comics are a much better gift. TPB's are rarely collectibe, but the individual issues are liking to see a price spike once anticipation of the movie arrives...

The last time I saw a complete run of The Watchmen on ebay it was around 50 bucks.

I'll see if I can find you a set man...