Dealer wants over $600 to replace oxygen sensor in 2015 forester xt?

[LeggyBlonde]

2015 Turbo Forester, 100,000 miles, has been losing power on acceleration, hesitation/surge on HW and at lower speeds, for past couple of years, intermittent at first, but gradually getting worse. Had it checked a few times, starting a couple of years ago, once at dealer, once at local mechanic, was told by both they could not recreate the problem so could not fix. We did some research, cleaned the MAF sensor, seemed to help for a couple of months. Then starts up again, becoming more consistent within past year. Couple of months ago, at dealership, they replaced transmission fluid and flushed system, seemed to help for a couple of weeks before problem comes back worse than ever.
Finally, this week a check engine light comes on (actually the whole dashboard lit up, went into safe mode). Take it to dealership who says it's a bad oxygen sensor (did not specify if rear or MAF). Quoted 02 replacement charge of $620. Does this seem reasonable, considering the part should cost around $200-$240 and average labor for this service is 0.9-1.1 hours? (I may be off on the labor time, but this is what I found online from a couple of different sources.)
Does anyone know a typical hourly labor rate for a Subaru dealership? The quote for labor was $340 for 1.8 hours of labor, which would be around $190/hour. (BTW, the time between 1st call with the diagnosis, and the 2nd call saying it was fixed and ready to pick it up, was under one hour.)

 

[sjmdesigns]

I forgot what sensor we had to replace in our 2001 Outback, but it was around $450.00 (installed price) back around 2005. Those sensors are very expensive.