Your repair options are pretty harsh. Of all the great things about these cars, the air suspension is the one really problematic trait that causes some of the most frustration. First, you should know that the front wheel drive (aka, FWD or 2WD) version of the XT and XT6 never had the air suspension so it has the preferred “coil over” type struts. The reason you need to know this is because if you need to replace your air struts your absolute best bet is to try to find (and it isn’t easy) a FWD XT6 in a junkyard, or maybe one for sale in less than road-worthy condition. The struts from a FWD XT6 will fit perfectly in a 4WD XT6. New air struts run roughly $300US each!!! That’s right, $1,200US for all four corners! A broken down FWD XT6 with four good struts might be worth buying for as much as $400-$500US just for the struts alone.
If an XT6 is not to be found then you can use some creative engineering to slightly modify Impreza struts to do the job for the fronts, while Legacy struts or struts from an XT will work in the rear. There may be other solutions for aquiring coil over struts as well. Replacement of the struts is not a job to be undertaken by someone with limited tools/talent/knowledge for the job. You can provide the parts for a shop to do the job and rest assured that it’s been done correctly and that someone else’s knuckles got skinned, not yours. Sure, you’ll pay more but it might be worth it if you’re not mechanically inclined.
If you would rather replace the air struts, the $300US isn’t so bad if you’re replacing one every other year or so. To have an XT6 with a properly functioning air suspension is certainly a good thing, and if you can spread the expense over a long period of time that way, so much the better.