You're probably right, unfortunately. Most places would just kick the tires, check the oil, take it on a test drive and rod it around. Which is why I'd prefer to find someone who specializes in these, who might know of any common issues to look for.
Sadly, Mazdas ain't as popular as Subarus in these parts. But I'm half tempted to take it to JR's or Tim Vallie since they at least specialize in certain Japanese makes.
Does anyone on MAEC rock a Mazda of some sort?