I have a 2014 MDX but with only half that mileage. It's not had anything go wrong with it and I really enjoy driving it. These days for most vehicles 70K isn't a great deal of mileage since most vehicles are quite reliable nowadays. A 2014 with 70K miles isn't unheard of but that's fairly high mileage for a 2014 - higher than average. You can find a lot of 2014s with lower miles than that but of course they'll typically cost more than a higher mileage one.
I think the timing belt will need to be replaced at 105K or thereabouts and you should replace the water pump along with it then. The plugs will need to be replaced then also. You'd be facing that in 35K miles so consider that in the extended budget.
A couple of things -
- Do an extensive test drive in the vehicle with the radio off and pay attention to any weird noises, thumps, rattles, etc.
- Check all the body panels for alignment. Some had issues with poor panel alignment from teh factory.
- Check underneath and make sure it all looks decent and appears to not have been in an accident.
- If this is an AWD model make sure the spare's there along with the tire changing tools.