should know and do know are not the same, hell ive ran into people that dont know how to change a car tire just like op said mower wont last more than a couple years, i am one of those people that fixes an flips them as there quite simple. as unless they are super abused its going to be bad oil and a rebuid on the carb 80-90% of the time.
best think i can tell op is that change the oil/airfilter*/sparkplug* every year or more depending on your usage *will vary depending on usage etc. all of this i would expect any able person to do. paying someone to do this is ok but u should learn how to do it just incase of an emergency, an your gettin this item because of one so imo u should learn how it works and why. i would put my faith in that op could do this!! if not your going to spend more $ as shops norm go 60-75 for a simple tune up airfilter,oil,sparkplug for 10min of work tops, so even if it takes u 3x taht u just paid urself $60 an hr and most people dont make that.