I think I have spend upwards of £4000 on mine, but on the other hand I have had this year for almost two years, thats double what i've kept most cars before and four times as long as I kept the Porsche. I intend to keep a good while longer too, I can't think of anything I can afford that will come anywhere near as close. So over a few years of swapping cars I could have lost around the same money on PXing etc.
I've also got a lot of enjoyment from the mods, the car turns heads every time i'm on the road and there is not one golf I have seen that looks like mine.