We have historical data for TOTAL SALES, but not for search PPC program..
for total sales, we did get in Nov 04 70% more sales than Octobet 04, and in December 04 250% more sales than Oct 04 (or 2 times Nov 04)
So I don't think we are that much off taking in consideration TOTAL SALES, but maybe for search PPC programs.
How much are you estimating conversion rate will increase...
Let's say your October revenue share was 30%, do you think it would go down to 15%?
If anything, some tweaks in the creative are made and this can help to offset other advertisers raising their bid prices.
Last year January was phenomenal and, IMHO, can be an even better time to be aggressive when bidding since it seems many other advertisers are pulling back or have spent so much in December that they have to cut back in January.