Pentax digital batteries are easy to come by. Radio Shack carries them, They also fit the Canon New F1.
Remember, also, that blue sky is Zone V, so if all else fails on a sunny day, meter the sky, do what it indicates, and it will most probably be fine.
I like the idea of knowing exposure without a meter. We try to teach than in our workshops. It's easy to learn, and will improve your seeing immensely.