A 4x4 is always worth about a grand wholesale. So thats not a bad price. The only thing i would inquire about is if the shutters behind the dash that control air flow direction have ever been replaced.
As a dealer the most common problem i have seen with high mileage Explores besides the more common ones already listed above is that. And its a pain and half and you would not want to try and do it yourself. The entire dash must come off.