i think 150miles on 30 quid may be a tad optimistic, dont think mines last anywhere near that long.
As a ref, had my TT for about 6 months now. Expenditure to date:
Insurance: £1800ish
Tax, MOT etc etc.
Service (inc cambelt): About £400, being done this weekend.
Mods:
Boost gauge: £50ish
Apexi induction: £50ish (second hand)
Dash: £100
Turbo Timer: £100
19" Rims and rubber arriving december.
Luckily the car came with a big exhaust and skirts etc else the list would prob go on.
I think running costs are one thing (quite reasonable considering the power of the car IMO), its the mods that will kill you.
I think everyone says they won't etc but when the bug bites, it bites hard!
:flame Dev