Well one other possibility that no one has posted yet is to use a thyristor flash unit. It wont be as good as a hand held light meter, or a built in meter of a camera, but since you said you mostly have problems guessing exposure indoors, this type of automatic flash could work for you. Just read off the back exposure guide number diagrams which would indicate what settings you should be near to get good exposure. All you have to know is aperture, distance, and film speed. Syncing speeds vary though. The thyristor automatically calculates how much flash is needed for proper exposure.

This could be 2 birds with one stone if you dont have a flash unit as well.

That being said, I would recommend the light meter I use routinely, the Polaris 5. It comes with all accessories and case included, backlit screen, 1 AA battery powered, 5 degree spot meter(would have been much nicer if it was 1 degree), and is very compact. I got it LNIB for around $160 or so a bit back.