As others have said, at 200-300 hrs a month I think you seriously need to increase your budget, preferably buy new.

2nd hand trucks in this price band I simply not going to stand up to this sort of work load as being already substantially through there working life. You may be lucky, with careful purchasing and rigorous maintenance but odds are against it.

Stick to premium brands, don't be tempted by cheap Chinese, maybe look for some ex-demonstrator or low hours ex rental units