If the cut out is an inch deep or less and is rounded off I would consider it. Any cut out much deeper than an inch, or anything with straight cuts and sharp edges (a 'pizza' style cut out) I would avoid.
Buying any damaged cymbal is a gamble. I've bought 3 with small cracks. because they were cheap, and I wanted to see how it would work out if I repaired them myself. An 18" crash with a small edge crack gave up the ghost within a few months - the crack just continued even though I carefully cut out a round section from the edge and sanded it smooth, A 16" crash with a similar repair is still good some 5 years later, and a 12" china splash that I cut out a round 'ozone' style hole in the bow is still intact but sounds like shit - it sounded better before I cut it, for some reason cutting out the hole made it sound like I'd plastered it with 3lbs of tape. I don't use it because it sounds crap so I can't comment on life expectancy - but I suspect it wouldn't last long if I played it regularly.
If the cymbal is dirt cheap and you are willing to accept that it may not last long it may be worth a gamble, but don't expect it to sound the same as an unmodified cymbal - you may get lucky, but I suspect the odds are less than 50/50.