I have also made the same mistake, and I would think that some sort of check box to confirm would be good, as lag can also cause accidental buys.
Either that, or make the 42k karma items accound bound so other characters can use it, or able to be sold back or traded for another piece. Getting at least some of the karma back which would otherwise be wasted would be nice… it’s not easy to get 42k karma, and awfully demoralizing when you buy something you can’t use.