The GTI/Edition 30 is not an expensive car to run. It may be relative to some others but compared to some I have had in the past it is relaively inexpensive.
My previous car was a Jag S-Type R (4.2V8 with SC, 400bhp/400lbft), the rear tyres lasted 10,000 miles and were ~£250 each, the fronts lasted about 20K and were > £200 each (work that out... 8 rears and 4 fronts in a year), servicing every 10,000 miles (iirc) was a minimum of £300 before they lifted the bonnet, Group 20 insurance, and 20-25mpg... I loved it but couldn't justify the cost over 40K miles per year.
The Golf on the other hand in the year I've had it (33,000miles) has needed 2 tyres at ~ £150each (I need another full set and they're being fitted on Friday), one service (its about 2,000 miles from the second one), cheaper insurance, ~30mpg...
Now, luckily someone else pays for my fuel but even so...
Look at the price of the car when it was new and judge the likely running costs from that... a £60K car like the Jag definately has £60K car running costs even when bought used for much less than half of that... the £20K Golf on the otherhand has similar running costs to most other £20K cars but will be more expensive to run than a £10K Polo...