Hi OP - I'm the PP that's in the same boat as you. I found a fertility monitor at CVS last night. They are an investment: $200 for the monitor, $50 for the 30 additional strips. You can find one online for $50 less (target.com) but I didn't have the time b/c wanted to start this cycle.
I read the directions last night and it is my understanding you can start the monitor at a later day in your cycle, as long as you're still within the 4-5 first days of it. Normally, you start the monitor on your first day -- but testing doesn't start until the 10th day (or so) so you are fine if you want to go buy one. Just be sure to program it as day 2, or whatever the day is for you.
Best of luck! Oh, and the monitors are kept in the pharmacy.