If you are going to take incident light readings only, then any of the older cinema and ordinary light meters will work well enough. If you are going to shoot slide film you will want something that is dead accurate, preferably with a spot meter. That will also help if you want to expose according to the zone system etc. I don't use the zone system much for 35 mm, but I have a Sekonic spot meter that I use with my Mamiya RZ equipment for 6x7, and my method is to select the placement of tones in the scene. It works 100%, and is the only way to make sure you get shadow and/or highlight areas properly exposed. If it costs you a slight bit more than $100 then it will still be worth considering. You have to accept that it will slow you down considerably, and will not really work for fleeting subjects such as street photography in widely varying light levels. In that case, I would simply go by the camera light meter, and note if there is a trend to under or over expose for certain types of lighting conditions and then compensate for those. For instance, your camera might sacrifice the shadows if there are large bright areas in the frame (white walls etc.), as it is working on an average metering. You may then prefer to meter off a known or guestimate reference, and set your exposure manually. Metering is an art in itself, and one that you must learn and practice if you want to achieve success with your photography.