OPKs are expensive when used regularly (every FW until positive) for several months, but is it worth the cost? I would like help determining if BBT and CM is enough, or is adding OPK the way to go. I'm aware that all used in combination is best, but are just BBT and CM enough? Which OPK brands are more accurate and affordable? I find the double line OPKs difficult to read accurately and prefer the ones that either say LH surge or have a smiley face. Please comment if you had a successful experience with a different method or combination.