Fertility monitors?

I'm 33 and TTC baby #1, my husband is 33 too and we've been trying for the past 2 months. I've been researching fertility monitors (we've only used Glow so far) and I'm wondering if anyone has any experience using them? (Clearblue Fertility monitor, Ovacue and the like). I'm thinking about getting one but they're sooo expensive, wondering if it's worth it- any thoughts would be much appreciated! :)