Sorry to hear, J,K&L'sMum
I agree with Nomie, Oracle OPKs are good and cheap.
I used about 20 this cycle as well and it was totally worth it — if I had only been testing once a day I wouldn't have known what was happening, I would have gotten a faint line one day and a faint line the next day and thought maybe O was still coming. Testing a few times a day let me see my surge actually start in between. I don't feel like I'll need to do that every cycle but it's easy if they are $13 for 40!