[CaptLego]

400 to 500 chips should be more than enough for any game with 6 players. Your chips will be non-denoms, so you can play for any stakes. If you start each person with 40 to 50 chips, that's only 300 chips for 6 players, leaving plenty for additional players or rebuys.

So...
If you use 1 color as the small blind or ante, and the 2nd color as 4 or 5x the first
for example color A=.25, color B=$1
Give each player 20 A's = $5 and 15 B's = $15. for a $20 buyin.
That only takes 120 A chips and 90 B chips. You can use chip C=5x chip B (= $5, in this example). 4 chip B's makes a rebuy, so 25 of those chips would let everybody rebuy once.

For a $40 buy-in (better, if the BB is $.50), you could give each person 20 A (.25), 20 B ($1), and 3 C ($5). That's 45 chips totaling $40.

So with 125 color A, 125 color B, and 25 of color C, you'd have plenty of chips for your game. 25 more C's would support 3 rebuys at $40 each. That's only 300 chips so far.

If you want to buy more chips, I'd suggest just getting more of these same colors. You don't really have much use for a fourth color. If you expect to play limit games, you'd probably be best with a lot of chips of the same color. If you want to add more players, you'll need more of all three colors. If you want to support more rebuys, you'll need more of the bigger chips.

For 400 chips, you might try someting like;
A 200
B 150 or 125
C 50 or 75

For 500 chips, how about:
A 250
B 150 or 175
C 100 or 75