hi mate as long as they have been properly looked after they can be very reliable cars. Ideally you want one unmodded but that’s not easy to find these days. If it’s been modded say past a cat back and hasn’t been mapped I’d be suspicious. I’d personally stick with the pre 06 models for the reasons siluro outlined. Rust is a major factor on many Subaru’s that don’t live in garages and are used through the winter. Checking rear arches, sills front radiator support etc. Servicing is a big one too make sure it’s had regular oil changes etc etc, timing belt should be done at the mileage your looking at but scan paperwork cause it’s every 50,000ish miles or 5YEARS. Awesome cars but, I’ve had two wrxs an 02 and my current 04. Biggest issues I had was corrosion cause they were/are kept outside. Parts for them aren’t crazy expensive insurance is very reasonable for what the car is and there is a great community and aftermarket that supports the brand.