Score modifiers are a great way to make more studs. Aim to get the red bricks that unlock each one, and activate all of the ones you've unlocked simultaneously. The purple stud, which appears next to the shop, usually gives you 150,00 or so. So, with modifiers:
2 x 15,000=30,000 2 x 4 x 15,000=120,000 2 x 4 x 6 x 15,000=720,000 2 x 4 x 6 x 8 x 15,000=5,760,000 2 x 4 x 6 x 8 x 10 x 15,000=57,600,000
That's quite a lot of studs! Also, unlocking all the characters/hints only costs around 4,000,000 total, so you're set.