I own a conversion optimization company and I just got an offer by a potential client to handle ppc optimization. They currently spend around 100k for the PPC but they have budgeted millions in the past. They have a ppc management company that handles their PPC. They need me to handle the optimization of these campaigns by doing a/b and or Multivariate testing on their landing pages and experiments on the campaigns themselves, all to increase conversion rates and ROI. What I need help with is how to price this service. I am thinking I should ask for a percentage of profits made after increasing conversions rates. Do any of you guys have any experience on this type of pricing model? Should I charge a percentage on the profits made/saved if so how much? Should this roll over every month? Contract? Any advice would be epic.