I personally prefer bar gun setups as opposed to the big machines. The thing is, most commercial ones you see have to use a cold plate. This plate needs to be submerged in a ice bin and loaded with ice for a bit otherwise soda is flat.
I kinda like this companies setup. It uses a mini-refridgerated unit instead of a cold plate.http://www.athomesoda.com/sys-tmpl/door/
Under kitchen bar guns link on that site.
Otherwise you could search around for wunderbar products.
Hope that helps.
Oh ya..I forgot. Home gun setups I've seen range from used on auction sites at 500-1500. This new one above is 1700-2200. As far as syrups they are in huge boxes that last awhile. Average cost for a glass of soda from the syrup is about 5 cents give or take. Plus, you can mix the carbonation/syrup/water ratio to your exact likings.