I bought a bunch of ebay cheapies to help me save some $$ due to my POAS addiction while TTC. The cheapies helped save money, but I definately think they are not as sensitive as FRER's. I got my first faint BFP 9DPO with FRER but didn't get a positive line on the ebay cheapies until a day or two later, by that stage I'd already got a BFP on CB Digital.
On the other hand the internet cheapie OPKs are fantastic, they worked just as well as any other pharmacy or supermarket brand OPKs.
All the best for your BT results, hoping for a BFP for you very soon.