Are you sure you need one? From your numbers, you are only doing $500 a week in dine in (5% of 10k). Even if 20% of that is drinks, you would only sell 75 $1.50 sodas a week. It costs about $50 for 30 gallons, so that is about 190 20 oz sodas, or 26 cents each. Add in the cup, lid, and straw, employee consumption and loss, and you are looking at around 45 cents each (higher by about 1.5 times if you add in free refills).

Figure a

crappy used soda fountain off craigslist is about $400, and an ice maker is

about the same.

This one looks good, but the cost is $2500. Add in $500 for plumbing, you are looking at a long time before you recoup any savings.

75 sodas a week at $1.49

1.49 - .45 = $1.04

$1300/1.04 = 1250, so that is 20-25 weeks just to pay for the stuff alone (some people will want PET bottles)

$3000/1.04 = 2885, nearly 10 months in this case. (Also keep in mind the cost of additional inventory.)

Subtract the difference between the profit on your 20 oz. cokes and the fountain drinks, and you are looking at 2 years to see any positive gain from switching. I did estimate on the high side. You could reduce costs by shopping around, searching for rebates, using generic mixes, and cheap cups, but all of that takes time that could be used more profitably elsewhere.