'04 Sienna not starting properly

My '04 sienna has 40k miles and is not firing up right away like it used to. I’ve had the battery checked at an autopart store and it is working properly so i suspect it’s the starter since it’s making some clicking noise (like if the battery was dead) when it doesn’t fire up right away.

The mechanic is telling me that i can’t replace the starter with a refurbished one cause they only last 1 year and should go with OEM Toyota part at $300 + $170 for labor so total to replace starter will be in the $500. Does this pricing sounds reasonable?

It’s weird that the starter will go bad at 40k miles but if it has to be replaced should i follow the advice of the mechanic or go with a $70 one remanufactured?

I’ve only done the oil changed every 5k at dealer since i bought it new so could it be that it needs a tune up and that’s the spark plug or else that’s going bad?

I also noticed that the side doors are not closing automatically all the times, mostly when the car has not been running or the engine has been turned off. Sometimes i’ll push the button and they would open and close sometimes not, both issues started around the same time.