Does it look like the previous owner cleaned his furnace every year?
If not then you don't need to either. If it looks dirty enough its
quite easy to shut it off and clean it yourself unless you consider
$200 worth not having to do it yourself.
I always kept my own 30 year old gas furnace clean myself. It looks
as new as the day I had built the house. I asked the gas company to
inspect the heat exchanger tubes and innards two years ago and he said
everything is in pretty good condition.
I have a newer gas furnace; the annual service charge is now $69.00. I
generally have the furnace professionally serviced once every three years,
and clean it myself in between professional visits.
>