Hi,
It's all about the math. The "quality" of the lead is measured by how effectively and cost effectively they convert to sales. Tracking cost of a lead is not enough by itself, you need to track conversion to sales too. Then, keep doing what works and stop doing what doesn't!
I'd make sure to track evrything you spend money on separately so you'll know what works and what doesn't. Sometimes you may find inexpensive leads actually convert better than expensive ones.
It's all about the testing.
For Internet leads, I like to get "organic" free traffic first before spending money. SEO (search engine optimization) is a huge topic, but I'm having good luck with video these days - sometimes a video can get ranked by Google in 10 - 20 minutes.
