Price can vary pretty drastically based on not only mileage and condition
but color! Miata.net is a great place to look to learn prices. Might be
relitively high but are equally likely to be better cared for. I don't feel
they are overpriced there generally, of course you get the occasional person
who thinks his or her particular car is worth a fortune. I would say
normally aspirated 92's (running cond) prob go from $2,000 to $8,000. Forced
induction cars probably add about $2000. This is only my gut feeling after
watching prices for 5 or 6 years on these little cars. Autotrader.com seems
pretty user-friendly.

Good luck,
Chris
92BB&T w/133k running strong!