How long would it take for the average mechanic to change the pressure sensor, and how much would it cost for the replacement? Thanks

 

boost pressure? oil pressure? Either are very simple. The boost sensor is a whole separate piece bolted to the pass side of the engine bay, and the oil pressure sensor is on the rear iron on the drivers side... its a big bronzish mushroom looking thingy.

Your best bet for finding replacements is either mazda themselves, a junkyard or the parts section of this forum..

 

Being NA I dunno nuffin bout dem boost sensors, but the oil pressure sender is a piece 'o cake...especially if you don't have PS or AC installed.
5 minutes max on the stripped car, maybe twice that on a fully loaded one.

If the mechanic is union or works on book rate figure 4-5 hours.