@muffincake – Yes I do have an idea about how many coins there are total. And, as a fellow obsessor, I have chosen not to obsess about this. Kind of like choosing your battles — seems a good idea to choose your obsessions.
The main reason that I chose not to be obsessed about coins was that I predicted that, since Rovio had finally made an achievement for 1000 coins, that they were going to have quite a bit more than that, maybe 10-20% more, so that non-ABN-non-obsessed people could get the achievement. Since in order to do that the number of coins being added and backfilled was going to get messy, it seems better to funnel my obsessiveness a different direction.
At any rate, to directly address your question, I know relatively precisely when I hit the 1000 coin mark and how much were left. I had to create a new account and start again from scratch. I raced through chapters 1-4 as quickly as possible (probably only three starring one out of every 6-7 levels, by chance), succeeded in opening up all the reward levels (the only reward level that I finished/ gained any coins for, was Chewbacca, because I wanted screenshots for all of the other levels showing all of coins), and finished MYD. Now I have been going through and three-starring the remaining levels in order to get all of the coin achievements. I three starred chapter 1, half of chapter 2, and then got the 1000 coin achievement. ?! I was really surprised. I had gotten all of the along-the-path achievements, but I had 2.5 more chapters of three-star level achievements and all of the reward chapter coins but Chewbacca still left to glean. I haven’t done the numbers, but this should give you some idea from a different direction, and leaves me content about not fretting about this.
I hope this helps and doesn’t feed the fire of more obsessiveness!