Where is Appollo? In the U.S. they are in the same area as pregnancy tests. All of our pharmacies carry them and even some grocery stores. If you cannot get them there, try online at saveontests dot com or babyhopes. Online they run between .50-$1.00 ea
If you have a costco, they sell them too. I think I got 10 or 20 (can't remember) for around 10 bucks.
grocery stores, target, walgreens, walmart, kmart, cvs, just about any major discount type store or pharmacy will have opks.