Noa Gertin of Palore has recently completed some interesting research on SMB PPC ad spends. They looked at over 3000 SMBs who advertise online, on different websites, out of which they focused on 300 businesses who also advertised on search engines in the past 5 months. They filtered out nationwide chains and all SMBs with more than one office location and only looked at PPC advertising, not longer term advertising commitments. That not withstanding, the drop is significant.
Their methodology does not allow one to extrapolate all SMB spending in all internet mediums but gives an idea of the rapid contraction in a certain sector of the advertising economy amongst a clientele (the one store operation) that can make these quick decisions. I would love to see a plot comparing these 300 with the other 2700 businesses that were surveyed to see the difference.