If you wanted it pristine, yes £10k maybe - if it needs a lot of replacement including an engine rebuild.You could easily spend 10K again getting this car back up to scratch, everything will need replacing and all the parts have M tax. I would make an offer of 6-7k justifying why.
But the reality is if you want a pristine car you probably wouldn't start with a 134k miler. Therefore you'd probably never commit £10k to it. You'd buy it as a cheap way into a Z3M and get it as nice as possible within reason. If it really needed an engine rebuild any time soon that would be the one thing having me head for the hills. Otherwise I'd probably keep the right side of 150k and hopefully out of trouble putting 3k a year on it over 5 years before hopefully being able to afford a better one.