Opinions differ, but my thoughts are buy on condition only, and lay aside colour & CC preferences as secondary box-ticks. The real life target is to get one not yet dissolving, and get it sorted out to prevent dissolving…if it’s a Keeper.
The NB and NBFL (Face Lift) have much in common…I have an NBFL. Pretty much a Cher plastic fantastic nose job really, but later NBFL’s came with more showroom blobby toys.
It’s crucial above all considerations to be pretty forensic about these years…so much is on Googly regarding hidden rot.
3k is quite an acceptable sum to nail a wee corker Simon, but be prepared for a long haul hunt. There are so many shiny sheds out there with more Daily Record ( or probably Sun) and plastic padding for sills now…including the all important engine bay chassis rails.
Equally, honest (relatively) rot free plug and play examples are out there.
Whatever you end up with, you will be buying into a global legend!
I’d recommend watching a few YouTube Mx5Restorer videos.
Check DVLA MOT infos. Look for gaps in annuals, and look for cars that fail on rot one day, and “pass” (cough cough) the same or next day. They smell of bodge-mobile unless a minor patch weld was required or something.
Check my other 5, a rotten Mk1 Reg L483 LNA for one example I’ve owned for 14 years. It was laid up for a long time till I had it (photographed) 3 months nut and bolt restored it nearly 2 years back.