In all painting mediums I've ever done, there is an initial tendency to be stingy with the paint. Yes, it is expensive, but looking back over 30 years, you will waste far more paint (in the form of unfinished paintings!) if you do not use an adequate amount of paint from the start. In cold wax medium painting, you can extend your oil paint quite a bit, adding up to 1:1 with cwm. This, in itself, is a way to extend how long your paints will last.