I agree on MAF (and o2) passing per FSM and still be working properly, since they didn't mention fuel economy
Or in other words, I have 1 MAF really being a gas consuming *** part while it only is .1 Volt higher per FSM test.
I also noticed the ''willing'' of this part to rise in Voltage fast (u need a scanner for this) was a little higher and easily over 4 Volts.
The other 2 MAF I tried, one from a scrap car and one from a scrapyard, atleast made the fuel smelling go away in the drive through of McDonalds, but it still wasn't very economical.
Then I came across another MAF from a friend, from a known good (but turbo-blown) setup and all seems to be ok.
Since a new MAF is just €510 euro's overhere at the dealer, spending 100 euro for all the second hands wasn't that bad.
MAF's just suck and such pricing of the dealership, well, that gets you asking this question.
$100 for a new MAF would be reasanoble. Therefore, I recommend check e-bay, for some cars they are just there for 50-75 and I saw them even intermittent available for the B13 Nx2000 for similar price... Which is quite rare.
However, for the bad mileage there can be more problems and also weather conditions, thermostat, leaky exhaust, whacked o2 to name a few...