What to be afraid of in a Donor Mx5?

[danilo]

Have been looking to find a usable Miata/mx5 as a donor (Wet coast of Canada)
But seemingly these things are owner by Kids who think perhaps a bit too highly of them, as asking prices for a ~90 version is in the $3/$4000 range.
A bit much methinks for a very tired and too often rough condition ...24 yr old car..
Likely the only affordable ones are going to be either non running beaters (yikes!) or seriously damaged... again (too ?) oldsters.
What are the key areas to inspect on these rascals that would render them completely unacceptable for donor uses ? ie; critically broken or simply no longer cost effective (worthwhile) to rebuild ?
Thanks.