I've had my zed 12 years now and am fortunate in having a good relationship with my independent garage thats been looking after our cars for 10yrs.
They even try and source 2nd hand parts where it's an option.
However, I know what you're saying about running costs.
The consumables on our 11 Ur old Mini Cooper are verging on freeness in comparison to the zed.
As it runs on diddy 15 inch OEM rims, the skinny tyres can be replaced for the price of one of the 19' rears of the zed
It may not be in the same league as the zed but I still enjoy hooting around in it.
I think the only time where I'd really say there's no joy is overtaking and joining motorways.
So a downgrade need not be a life of misery.
Got a friend with a stage 3 tuned R35 who used a £700 Ford Puma for commuting and loved how chuckable and worry free it was to own.
Just the worries of buying a lemon as with any 2nd hand car though!