Oh but that is the goal! have your stock worth more then your set-up
as far as cats go tbh most are very predetory so may spook gar particularly at night. Sun cats might work. they stay large enough they aren't likely to become dinner and ime are pretty docile. Being as your newer to fishkeeping I wouldn't reccomend a Tig, they scare me they can be touchy with water quality. But can't get much more "WoW" then them. Thats partially why I actually picked gar to house with my spiney eels a few years ago.. i wanted something more "out there" then my reclusive eels.. and the gar have been a good mix for me.