[CaptLego]

OK.
So you already have:
200 green
250 black
50 purple

So you're set to run a 10 person tourney, giving each person T5000 as 20x green, 20x black, and 5x purple. You have enough blacks to colorup the greens, if you want, but not enough chips to support rebuys or addons.

This seems like a pretty good setup. But if you want to augment the set and stay focussed on tourneys, then you can add chips to support rebuys, and more players.

Just doubling the set would be great for 20 players, unless you want to eventually colorup the blacks or support rebuys. Otherwise, you'll need some bigger chips.

You might try this:
400 green
400 black
100 purple
100 orange

Then for 20 players with T5000, start each person with 20x green, 15x black, 4x purple, and 1x orange. You'll have enough chips for 20 players, the ability to colorup the greens to blacks, and still have enough for 18 rebuys.

With the same distribution you could squeeze 33 people, giving each 12x green, 12x black, 3x purple, and 2x orange. You wouldn't have enough chips to support rebuys for this tourney. Colorups would also be a problem. You'd have enough orange chips to buy back stacks of 40 greens, but precious few remaining blacks or purples to handle the remaining greens cleanly. (With a progressive colorup, you might make it.... upgrade some purples to orange, upgrade blacks to purples, use the freed-up blacks to colorup the greens....)

It's probably not worth trying to squeeze more than 30 or so players into a tourney with only 1000 chips. You just wouldn't have enough chips per player no matter how you breakdown the set.

So I'd recommend he purchase an additional:
400 - 200 = 200 green
400 - 250 = 150 black
100 - 50 = 50 purple
100 - 0 = 100 orange