Experience with dollar store hpt's?

Since I spent well over $100 on early response pregnancy tests last month I decided to switch to the dollar tree brand this month but I am a bit worried about their accuracy. Has anybody had experiences with them? Good, bad, same as the others? Is it worth it, or should I just cough up the dough for the $15 ones? Also, I noticed that they have opk's there now too and am a bit weary of trying them.