$4200 is definitely one of the more expensive options!
Another option is to choose your own exhaust and get Allstar Garage (ASG) to Verso tune your
ECU for $990.
I'm not sure about fitment on the MY09 but I suggest that you speak to ASG in Malaga.
There are a heap of options out there (eg: China Spec Exhaust for $600 plus labour, ASG spec exhaust for around $1100, X-Force systems from $1100 onwards, Butler for just under $2000 etc.) but I'm not sure what fits the MY09.
Hopefully someone else can help you out with specific experience with the 08/09 models but don't stress, you don't have to spend $4000 on an exhaust + tune!!