Amazing! I came to it today with just four stars remaining – all of which were actually comet stars, it turned out. First up was a Daredevil Comet on the Deep Dark Galaxy (killing the big Magikoopa without getting hit – easy!), and then I braved the Luigi’s Purple Coins star, which drained a good 8 or 9 lives before I nailed it. The last two (another purple coin one, and Fast Foe one) were both waaaaaay easier than Luigi’s coins.
So, 120 stars! Just have to kill Bowser again now, I think!