Hi Karina,
I started out using OPK's then I found out about Maybe Baby from a friend who had been trying to get PG for about 2yrs, first time she used it she got PG.
This is my third cycle using it and I love it, I think it works out cheaper to use Maybe Baby, but if your worried about the cost I got mine brand new off Ebay for $50 including postage.
Hope that helps
xxx
Rach