Ok then, 200% means for every dollar you want to earn back $3, keeping $2 as profit.
Now to figure out what you can spend per keyword, you need to know your payout, (which I'm sure you do). For ringtones, let's guess at $12 per sale.
So here's the assumptions and the max spends to achieve them:
Your Investment: $1
Payout: $12
Target ROI: 200%
Target Conversion Rate (From Your Day One): 0.60%
Based on those Numbers the following results:
Maximum Spend per Keyword is $4.00
Maximum Bid per Keyword is $0.02
Which means at a payout of $12 per sale, you can spend $4.00 on every keyword at $0.02 max bid at an estimated conversion rate of 0.60% to get a an roi of 200%.
Let's make sure we're right by checking the ROI again:
% ROI = (Net Profit/Spend) x 100
% ROI = (($12 - $4)/$4) x 100
% ROI = ($8/$4) x 100
% ROI = 2 x 100
ROI = 200%
So the numbers DO work out. One thing to consider, you don't have enough data yet to make any decisions. Your first and second day numbers are not enough here to be statistically significant. You need around 1,000 clicks to make sure you're numbers are legit from a mathematical perspective, (more is better though).
So, why did you get 3 sales on day one and 0 on day two? It was a fluke.
This is the reason advanced ppc marketers are willing to lose money for the first couple days. They want statistically significant numbers, which is more valuable to them then losing a couple hundred dollars initially. Once you have some rock solid stats, it's just a matter of going into "robot test mode" and following all your rules for max spend, max bid and pausing the crap and testing the new stuff. (Hint, this is where a good bid management script would work beautifully, if you had one...)