OPK's- using different brands

I have been using 'ovunow' OPK's which I buy from my ob. I used the last one today and forgot to go and get some more! It is now late in the afternoon on the fri of a longweekend. It is most likely I won't O until after next tues but I would like to be able to check. the chemist has different brands of OPK's (really expensive!)... I just wondererd if anyone knows if it is ok to change brands mid-cycle or is this a bad idea? Thanks

i cant see a problem with it. i use first reponse brand that you get from woolies and coles for about $22 for seven. they also include a pregnancy test.

Thanks Shan, I will find something tomorrow. haven't got much to lose I guess. I am lucky that my ob sells the ovunow sticks to his patients for $1 each!