I have brought of TM, baby4you and wondfo brands.....Wondfo being cheaper.
I found with wondfo I would usually get a very faint line everytime I used them getting darker leading up to OV ( baby4you I only got faint lines leading up to OV ) both brands I would get positive results on them. I also used them togeather to see if the result would be different but both were exactly the same.
I use about max 4 per cycle min 2, but I know when Im most likley to OV so makes it easy.
You might use up to 8 per cycle if you have a rough idea when OV might happen
HPT's, I never test so cant reccomend brands....but FirstResponse is sensitive and quite cheap from supermarkets .......cheaper different brands online tho
Next time I buy some I would go to deal extreme web site (sp)?? apparently they have very cheap OPK's and HPT's
Hope that helps.