Yes. They are everywhere. As I said above, if you have a Dollar Tree dollar store they have them for $1. Also, you can get them near the pregnancy tests in any drugstore/ big box store.
What I’d do is start using them when you notice fertile mucus - slippery sensation, shiny mucus, stretchy-stringy, etc. Then, when it confirms ovulation, you take that as one sign of peak. You combine that with your mucus observation of peak - looking for the shift from fertile to, most likely, infertile mucus. Then, use the most conservative peak. Meaning if the urine test says peak is diagnosed on day 13, but you still had fertile mucus on day 14, but day 15 was dry, you use day 14 as peak.
Yes, you technically can use the test strips from the Clearblue monitor by themselves, but to be honest, they are not as easy to read without the machine. The lines on the Clearblue monitor measure a little differently than just plain opks. Also the Clearblue monitor test strips are quite expensive!
There are opks everywhere, at any drugstore. There are fancy ones, that are digital and give you a smiley face. These are the easiest to read - but also the most expensive, specially since at first, you’ll be using several test strips each cycle. Dollar stores also sell pretty reliable opks (and home pregnancy tests too actually!), OR if you want to buy opks in bulk for REALLY cheap, there are several places you can buy online. I’ve bought from both Amazon and ebay before. I usually use the Wondfo brand.
The trick to reading opks is that the second line on the test strip has to be as dark as, or darker, than the control line. That signals that you’re about to ovulate (or get a peak) within 24 hrs.
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