The no load speed of every drill is printed on its casing. I've done a lot of second hand drills and rarely had them fail on me. If they do, I keep the good part [motor or gearbox] and if one gets damaged in a fight I have a spare motor, or gearbox, to use in repairs. If you have lots of money, by all means buy new [although I think Argos cordless drills are more than £15 each, but that might be just my store - 18 V drills start at £26.] but new drills can also fail when they get hit hard.