How many star coins are there in Super Mario 3D land? It's easy to know how many there are in the regular levels, but with the bonus boxes it's much harder!
There are 285 Star Coins in the normal levels and 50 Star Coins in the bonus levels.
However, since StreetPassing with other players allows you to "reset" mystery boxes, letting you collect their Star Coins again, potentially there's an infinite amount of Star Coins, however you can only accumulate up to 999 star coins
In any case, you'll need only 290 Star Coins to unlock every level.
Well I have completed the game fully, even the last level World 8s with the golden flag, and I had 302 star coins when I completed it. However when I played it earlier I played some purple box levels and got some more star coins. Now I have 305 so there must be more than that - I'd say around 310 or 320.
The purple box levels regenerate every day. You can do this by playing the next day or just changing the date in ur 3ds settings. And yes while most yield a ghost star coin, one or two will have actual star coins you can receive to raise your star coin count. I'm up to 312 star coins and am still getting more star coins every time I change my 3ds date.
I just got done beating this game thoroughly and I have only managed to get 300 Star Coins. I have beat every level with 3 stars each and beat all the bonus levels, or purple square levels if you prefer. When you try and do these bonus levels again it will give you a ghost star, so you cannot keep getting them until you have 999 Star Coins. So I believe the answer is you can only get 300 Stars Coins.
I don't know how many there are total, but the purple cube levels respawn every day, and the ones you've already done will have ghost cubes, while new ones you haven't done will give you star coins, you can tell the difference between the finished and unfinished levels easily, upon entering one of the screens will show how many coins are in the level, if you have the coin, the coin image will show, if not, just the outline of the coin will show. Since the levels seems to change randomly from day to day, you won't know if you've completed that bonus level or not till you enter it.