Everyone here has been so helpful to me that I thought I would post some info about an item that we recently purchase and really love. I have always wanted the ability to have fountain soda in the house. I had looked into the post mix systems (similar to what you see in McDonalds) and while I know several people have them in their house it seemed as though the cost could be high, it took some work to put it in, and with all of the boxes of syrup it takes up a lot of room. I started reading about the Breakmate and decided I would give it a try and we love it.
Here is a picture of ours: http://blackcows.com/breakmate.JPG
One limitation is that it only allows for 3 flavors but because we have a button that supplies only soda water we have been able to purchase syrups and make many flavors such as Root Beer, Strawberry, Cherry, Grape, etc. and by adding Vanilla syrup to Coke we get Vanilla Coke we can add Cherry to get Cherry Coke, etc.
One other limitaion that I though may be a concern is that the drink sizes are fixed. On my machine you can either select a small (about 3 oz) or a large (about 6 3/4 oz). This really hasn't been an issue at all. If you want 12 oz you just push small 4 times, in fact we rarely switch it to large.
I was also able to purchase the Coke logo cups you see in the picture at the local Coca-Cola plant. I purchased 2000 for $55.00. The set-up was simple. You use a water line similar to that used for an ice machine and plug it in and you are ready to go.
One other advantage I have seen is that I don't find a lot of pop cans and bottles with a few drinks taken out of them. We have three kids and quite often they have friends over and it never failed that I would find several bottles of pop laying around with a few drinks taken out of them. Now I tell the kids you can have as much pop as you would like but you can only take a small drink (3 oz) each time and now we have virtually no waste.
You would be surprised at how compact these are. I knew the dimensions when I was looking for one but I was still pleasently suprised when mine showed up with how compact it really was.
I found a local source that sold these and got mine for $375.00 but you also find them on eBay.