Demand that the retailer provide verifiable specifics about maintenance, guides, producer information and a history of all completed repairs.
By making a visual inspection on the equipment to find any noticeable signs of neglect, abuse or disrepair, you'll be gaining the information necessary to make an wise selection. In the event that fixes will be necessary, setting up a detailed notation will assist you to go away and look at your choices without fear of forgetting anything once you are away from the item under consideration.
If an offer that may be way outside of the typical range is manufactured, there is motive for legitimate suspicion. Check all verifiable details including the credentials of the proposed retailer to ensure that everything is open and above board. It is better to be safe than to end up sorry.