Just FYI, they are more much more than just a few dollars more: These are less than a dollar a piece:

http://www.amazon.com/gp/aw/d/B0002YIQEQ/ref=mp_s_a_1_5?qid=1441652255&sr=1-5&pi=AC_SX110_SY165_QL70&dpPl=1&dpID=416a9QkaKeL&ref=plSrch

I don't know what OP bought but these are linked to from /r/birthcontrol

I like these ones. Same ones my local women's health clinic uses.

iirc these are the ones I had ordered, and I had no issues with them, but to make sure, if you get a positive, I would confirm with a storebought First Response Early Response. :)