I too have the Pure Freedom setup you're looking at and it's very good. And like everyone else I would advise getting a van.
However, If you're strapped for cash then get the system and start using it in your car and then progress to a van when you have the money.
The trolley can easily (and successfully) be adapted to be used as part of a van setup. That's how I use mine. So the trolley won't be wasted. You will get fed up with lugging 25l barrels around, but if cash is an issue then you've got to start somewhere. And it's not a bad place to start.
You may consider getting a gardiners backpack to start with as an option?