I agree. Jayco does make a good product. The founder, Bontrag (now deceased), and his family were/are all Indiana Amish and the company is still family privately owned.
Jayco is not a top of the line trailer, not fancy with lots of frills, but practical and good value for the price. It should make an excellent family starter trailer if priced right and IF it was maintained.
As cloydmark suggested, a stick built trailer that age can be excellent or the framing members and floor, which are wood and plywood, can be rotted fiber. Climb up on a ladder and on the roof and inspect every seam. Also inspect all the window and door frames. When they are neglected in warm climates and the caulking has dried, shrunk, and cracked a trailer used or stored outside will have water intrusion and lots of rot. Also inspect carefully for evidence of water stain on ceilings including cabinet and closet interiors.
I think Jaycos used quality Dexter running gear not Lippert and ChiComm crap.
Your signature indicates you live pretty close to Middlebury, it might be worth paying the owner to tow it to Jayco's service center at Middlebury and have it inspected in their shop. An hour or two of shop labor might cost you $200 and potentially avoid an expensive mistake.
On edit: Pay no attention to the seller's report of what the trailer weighs empty, loaded, or in between. Read the GVWR which is maximum loaded weight off the VIN decal or plate on the front of the left side. Always assume a trailer will weigh very close to GVWR when loaded for travel. Trailers don't weigh empty weight, even brand new and dry the day they leave the factory.