Generating leads from PPC and Alternatives

PPC lead generation and alternative methods.

[nadmedia]

When trying to generate a lead, do you generate leads from a ppc campaign or simple purchase the lead from a lead generation company? I do both and find that purchasing a lead from another source is cheaper, overall. The cost you don't see right away is hidden in the quality of lead. I prefer to generate leads from PPC campaigns to insure quality but find it more and more difficult for my ROI.

Successful PPC programs:
Yahoo, MSN Adcenter, Google
I do well with Verizon and a few other small ones.

My question to you all is:
What are some good alternative PPC programs (methods) and what are some ways to keep your CPC down by generating the same if not more traffic?

I know the question is broad, hopefully we can think outside the box to come up with an original approach to finding the solution.