[Wetzel]

Some math.

They buy them in cases of 24 for $10.50, or $0.43 each.
They sell them for $1. That means earnings of $0.67 each.
$13.50 per case.
They go through 7-9 cases a day. $94.50-$121.50 a day.
5 days a week. Thats $472.50-$607.50 a week.

A quick google search reveals that a simple bottled drink dispensor can be bough for between ~$1400 and $3000. It is a high up front cost, but looking at the above numbers, that is three to six weeks of income. If you convinced the school to let you use power and supply it yourself, it appears to be a good money maker. Good call on using fruit juice, a lot of schools are removing sodas from their machines or turning them off durring the day.

If you use 30 weeks for the school year, here are some yearly totals.
1050-1350 cases @$10.50 each - $11,025-$14,175
Income per case of #13.50 results in $14,175-$18,225 after purchasing the product. Even if you subtract the price of a good vending machine, $3000, it still looks like you will make $8,000-$11,000 your first year. Thats enough right there to build a robot and goto a local regional.

If you have more details, please share.

Wetzel