So 0.40/lead * 60 average calls to be succesful. So $24 per succesful lead. Plus ofcourse 60 * average call time, say 3 minutes, that means 3 hours investment for 1 sale. I made up those numbers, so you could probably refine the calculation a bit, but what I'm trying to show is that you probably waste a lot of time on bad leads. You could optimise by either using the time to get a better source of cheap leads or getting fast at filtering out the leads you have. Have you thought about texting? If that is not used a lot already in your area then you could try it. Nowadays with smartphones you can send links and have people open a website. Or you can use the internet to find additional information about the phonenumbers you get so you can target people more selectively.