What are people's opinions on the OPK from Dollar Tree? My hairdresser told me her doctor suggested the dollar store pregnancy tests because they're no different than the name brand ones that cost $15 or so. I've used those but I guess I'm not sure about the OPK. I have a longer cycle so I'm gonna need like 10 per month so I'm really not thrilled at spending over $40 a month. Does anyone have experience using them?