You might try a search on this forum, I know this has been asked and talked about several times but I don't remember ever seeing an answer. The filters are quite expensive but it was recommended to stick with the BC filters at least until your warranty was out. No reason to give them an excuse to try to get out of warranty repair.
I can tell you that not all BC dealers price their filters the same. My original dealer was MUCH higher on filters than the one I get mine from. I don't know why that is the case but it was.
I know there are several discussions on here about fluids. BC's fluid must be lined with gold because it is way over priced, something like $60 for 2.5 gal. Personally, I use Conoco but others have used Shell and brands from TSC or Rural King.
Use the search in this forum, you can find several threads on both filters and fluids.