Here are the OPKs I am using. You can purchase these at Dollar Tree, for just a $1 each. Which is about the cheapest I have found them, except for ordering test strips online.
Below is my opk from today, cd8. I just HAD to POAS, so I tested a little early. It came back negative, which is what I expected. For positive results there would be a line under the test "T" that was as dark, or darker, than the control "C" line.