I wasn't planning on using an OPK this cycle, but I think I'm going to anyway. You say you got yours on ebay? The least inexpensive the better, I say!
The other thing I'm planning on using this cycle is a personal lubricant called Pre-Seed. Ever heard of it? It is specially formulated to not harm sperm. I've never used it before, but since DH and I are trying at home this month, I have it to use. I had read on the internet that some types of moisturizers, KYjelly, etc, can harm sperm, so that's what motivated me to get it. The company has quite a few success stories on their website of couples that got pregnant using it!
Babehopes!!