Then an idea struck.
Have you ever seen those large containers of 'natural spring' water? I used to stack them when I worked at the supermarket - People who go out into the wild camping and people that live outside the town water supply buy them for safe drinking water - And certain people that don't trust tap water also buy them because it's basically bottled water bought in bulk.
Anyhow they come in different sizes but it was the 10 liter container that got my attention...10 liters? That's how much cordial you get out of one bottle of concentrate. If I poured 1 or 2 liters out and added cordial concentrate in I'd have a container full of cordial! And these containers have taps on them so I could dispense it into a glass of a bottle with ease! Wow I was onto something :D
I bought the cheapest 10L container of water (price $4.09) I could find as well as a 1L (super concentrated) container of lime flavored cordial (name brand @ $3.99) which totaled $8.08. I got home and poured out 1L of the water and substituted it with the 1L of cordial and gave it a nice shake up. Success! It worked like a dream and the container fits into my fridge so it can be chilled.
The best thing is you don't have to buy the brand name cordial and you can make this whole idea even cheaper. Look after the container and you can reuse it, it's like a one time investment - Have you seen how much commercial drink dispensers are? This thing works essentially the same and it even has two handles on it.
Anyhow this is probably something people have been doing for a long time but I've never seen it myself so I figured I may as well share it (which you are also free to do if you want to). Some pictures of this set up are below.
The containers of water in the supermarket, note the handle and tap and that they are stack-able
The container with lime cordial, note in this picture there is a robust handle on the top