Yeah, go with a sodastream, but skip their syrups.
It's pretty easy to make your own soda syrups... might not get the pretty colours that some of the commercial ones have, but you can customize them to your taste. I've got this book, which has some great recipes, but usually I just experiment and make my own.
http://www.goodreads.com/book/show/1...-homemade-soda
Most of the time though, we just drink soda with whatever fruit juice we have around at about a 4-1 mix.
And yeah, lingonberry from ikea is pretty tasty.