Buy the games and dump them yourself There are a fair number of things you can't be certain of, mostly concerning audio. There can easily be small jitters you can't hear, or your bin+cue could have lossy audio if somebody took it and went iso+mp3>CDR>bin+cue (I know I've seen it done).
Of course that's just if your making a Goodset. If everything sounds good and seems to work correctly I suppose it's good enough