To me, it looks pretty easy to deal with the BP. Pay $10 once, and then either figure out the system and play a little every day, or if you can’t be bothered, pay a bit more to get the stuff you want and/or the next BP.
It’s not too hard to figure out how to use the rerolls with multipliers to maximize the BP XP you get from the challenges. I can usually get one legendary challenge a day, which already gives me 150x10=1500 XP, and that’s a level and a half. I try to get 700 or 400 for each of the remaining challenges, and do the 300 ones only if I’ve used all my rerolls for the day. All in all, I expect to be done with the BP in less than two months, comfortably.
The one thing that could put a wrench in that plan is if I skip one or more days. The multipliers accumulate for up to 5 days, but the rerolls don’t, so it’s much better to play a bit every single day than it is to let the multipliers pile up.
It would be nice if Funcom gave us a way to do something in-game to earn additional multipliers and/or rerolls. It could be something non-trivial, but it might be worth it.