Funnily enough, I own a 2005 MR2, so my advice would be to snap it up! I'd be a little concerned about its low mileage as things might have seized up or the tyres might have perished, but you can easily spot that. Very little goes wrong with them - I've had mine 2.5 years and it hasn't need anything other than regular servicing and a set of fresh tyres when I bought it. The rear subframe rusts and it's hard to gain access to this for a clear view, but I wouldn't have thought it'd be an issue on a 2005 car with low miles. The front lights can sometimes cloud up, but that's easily fixed. And if it needs a new roof, this guy is very highly regarded and will change a roof for a little more than £300: classics.honestjohn.co.uk/good-garage-guide/garage.../

It's hard to help with a value for a car with so little miles without having a clear idea on its condition. I've seen dealers asking £6000 for mint, low-mileage examples, but I wouldn't want to pay more than £4000 privately unless it's in exceptional condition. This place is good for advice: www.mr2roc.org/forum/index.php