Opks- where do you get yours? What's your fav?

Marquee • Happily Married 💍👑Mommy of a sweet boy 🧒🏽 and two angel babies👼🏻 currently awaiting our newest family members arrival ❤️8.25.18❤️
Where do you get yours? Which brands do recommend/ not recommend and why? I used the equate ones last cycle but I'm pretty sure they didn't quiet catch my LH surge or the line just didn't get dark enough for me to think it was an actual positive