Danavan.net: SEO & PPC Still Lead as Lowest Cost Inquiry Generators

While the data is old (March 2003), search appears to be the most efficient lead generation vehicle. The average lead from search engine marketing costs 29 cents. For email it is 50 cents. Yellow pages directories jump up to $1.18, and banner advertising jumps again to $2.00. Direct mail sits in its own order of magnitude, costing $9.94 per lead.