Hello welcome,
There are loads of cars out there ranging from complete lemons to some well kept examples, best bet is to just absorb as much info as possible and view lots just so you can gauge the market and what you can get.
Cars with loads of service history are obviously ones to go for as although they aren't super expensive to run and maintain you'll save yourself some money at the start, for instance if you bought something with no records of cambelts or a recent major service done it's going to set you back nearly 800 notes,
Your main hurdle will be you age with insurance, most companies will either laugh alot of charge you a couple of grand for the privilege of owning a turbo or wrx. Not sure how different a gx will come in at, being a 2.0l it could still be silly, maybe have a look at insuring it before buying.