MovingOnUp - 8:09 am on Jan 24, 2005 (gmt 0)

50-100% ROI and better is certainly possible. Due to fluxuations, I usually aim for a 100% ROI.

One of my most successful campaigns ran about a 1000% return ($500 spend, $5000 profit). Unfortunately, the merchant ran out of inventory and I haven't found a suitable replacement.

I haven't found any situations where you can just double your budget to double your earnings. I usually go in to each campaign with the maximum recommended budget and a maximum CPC that I project will give a 100% ROI. After I have sufficient history, I adjust the CPC, optimize the keywords and ad text, and let it run.