Whenever you buy a second hand car, expect there to be something costly to fix on it, be it brakes, gearbox, suspension etc within a year or so of you owning it.
That being said, get a mechanic to come along with you or take it to your mechanic if you're keen on buying it. Tell the guy selling you'll take it pending the mechanics opinion. RACV (or equivalent) checks are always helpful too. Cheap as well for about $125-150.
Economy wise theyre not too bad. I usually do about 11k/100L with the occasional spirited run.
Im probably too late in replying, but oh well.
Good luck, and hope to see another TRX join the ranks