As Bio already stated, the answer to this question is completely league dependent.
If you are in one of the major leagues underpinned by some mega coiners you will be picking up 5-7k from each brawl, quite regularly up to 6k from getting 200 PvP points in league PvP events and more from minor participation in other league events. And now due to the giveaway to all offer a significant amount of sapphires just land in your lap. Easily more than 30k for doing nothing (and potentially a lot more depending on how much the offer is used).
Outside of the big leagues you would get none of that and your only free sapphires would be from working your account very hard. It would be a completely different experience.
This is something some of us have been trying to tell you for a long time. That progress in the game is about joining the "right league" not about how hard you play your account. And alt in the "right league" would get more sapphires per week than a really well played account in another.
1. Could be over over 100k in the "right league"
2. Over a 100k in the "right league"
3. 2/3k on most accounts (what comes from easy participation in league events)
Also the question is also a bit loaded. It would only really make sense if players could answer it at the net level (which you couldn't track w/o a massive amount of work). If you get free sapphires from a solo BG event then you have lost more troops than you gained so those sapphires cost you a considerable amount of money. Same for things like the progress event. Someone could report massive sapphire earnings only for you to find out they bought many many packaged to fund the activity to gain them.
So listing out the events and what you could gain from them would be the best solution to getting the answers you asked for. If you then broke the sapphires available into categories for each event, the answer would then be hugely useful; as follows:
a) can be done for free by anyone
b) can be done for free if league progress is adequate
c) could only be done by spending more sapphires than the actual reward
I guess there is a final category as well (but w/o alts in a lot of leagues you won't be able to collect data on it), which would be:
d) sapphires gained from league offers