After trying a few tires, I stick with Schwalbe Kojaks. They are more than $25 (here in Tokyo), but I usually get more than a year of daily riding out of them. I got only one puncture on my last set, which isn't bad when I was used to getting a puncture at least once a month on my road bike.

I keep the Kojaks pumped up to 100-110 psi, rolling resistance is low, and they have surprising grip for slick tires, no sliding around in the rain. They are light, foldable, and here in Japan, they are available at most bike shops. Elsewhere it might be a good idea to buy a couple sets.