If it's cheap enough and passes a thorough check, I wouldn't think anything of it. That's got to be mostly easy highway miles unless it was used as a cab, which would be obvious at a glance and is an unlikely choice for such. As long as it looks to be in good shape and the only items needing attention are the obvious ones (brakes, maybe some suspension), you should be fine. Check all the fluids, check behind panels for prior crash damage, etc. If it rattles and shakes at all, move on.
I put 50-60k a year on a car (Japanese and American) and my 2012 SE ran perfectly, still looked good, and everything was tight and quiet when it was totaled at 204k. Unless something breaks or wears out, I do nothing but change the oil (synthetic every 10k) on my cars and they've always had few minor to no problems and I don't drive like an old lady. Machines are meant to be used and large miles means easy highway (unless used as a cab) and longer trips where everything is allowed to get fully up to temperature. I'd rather have a newer high mileage car than an old car with hardly any miles. Plus, if a car was so unreliable, they wouldn't have driven so much. My SE needed brakes for the first time and rear shocks at over 130k, tires about every year. Never even changed the wipers and I think I might have changed the air filter once, but I'm not sure. Still averaged 36 mpg/tank and burned little to no oil between changes. My Mazda 3 before it was kind of beat at 167k with worn suspension and brakes (and rust—figure out galvanizing, Mazda!), but ran great and never had a single mechanical issue. I know a guy who's far worse on cars than me and would get over 300k out of Cavaliers and Escorts. I realize the ST is more performance oriented than any of the above, so I guess I'll find out for everyone how they do in a few years.
