Yup Fretty, the ebay roller bridges look the same as the better quality ones until you have it apart and find the saddles are either wedged in tight or overly sloppy. I think I spent the best part of a morning with small files and a dremel making 1 good one out of 2 on my last build. Also the post spacing on them can vary enough to make it an issue. You can be lucky, I have bought a couple which were fine, I guess there are a few companies out there making them.
Used Schaller bridges and tail pieces on a few and give them a thumbs up, bit pricier but nicely made.
I've had good experience with Wilkinson strat trems, the block is actually steel rather than chitanium and a definite step up.
I've used Bigsby's, licensed Bigsby and chinese bigsby and don't see any difference to speak of. Again, if you want to spend the $ ...Duesenburg, the Les Trem is the best trem system I've used bar none.