After trying for 10+ months, I finally broke down and bought one (found the best deal on walmart.com of all places). We conceived on our very first month of using it. I took advice from one of the fertility books I read and we BD'd every other day of "high" - not just during the "peak" days. I did have like 10 days of "high" but that's because the monitor apparently takes its time figuring out your cycle. Supposedly the number of high days decreases as it learns your cycle. Good luck!
My only problem with it is that I only got to use it one month! LOL Not complaining, I swear!