I bought my 2003 Subaru Outback with about 120K miles on the original timing belt and gears as well as the original headgaskets. I already knew these had to be done when I bought it, and ended paying $2500 for both headgaskets (get Cometic gaskets) and head machining, timing belt, tensioner, idler pulleys, spark plugs, wires, transmission fluid & filter, Differential fluid change.
In my case when I talked to the mechanic after the work he showed me that my old tensioner was leaking and the timing belt had started cracking and the headgaskets had most of the black sealant material gone on the bottom portion. (I was lucky the timing belt or the tensioner hadn't completely failed) I would definetly get the work done as soon as possible if you plan to keep the car in your case.
In my case when I talked to the mechanic after the work he showed me that my old tensioner was leaking and the timing belt had started cracking and the headgaskets had most of the black sealant material gone on the bottom portion. (I was lucky the timing belt or the tensioner hadn't completely failed) I would definetly get the work done as soon as possible if you plan to keep the car in your case.