Hi Leslie and Margaret, welcome to the Practical Caravan forum.
Apologies for the delay in my reply, I somehow missed seeing your query but here goes............
Click Here to see a used tourer buyers guide which contains lots of good advice on what to look for when buying a caravan.
If you are buying from a caravan dealer check to find out what guarantee is offered with the caravan and if the caravan is a private sale ensure that the vendor has the right to sell the caravan and if possible get them to put in writing that the caravan is in good condition with no known faults, don't fall for the old 'sold as seen' trick.
Click Here for a basic price guide and make sure that the year of manufacture is as advertised, the used buyers guide will explain how to do this from the caravan vin number which will be etched on the windows in the bottom corners.
Ask to see evidence of servicing, a well looked after caravan will have been serviced every year by an approved caravan engineer or workshop, so if there are excuses about 'lost paperwork' walk away because there are plenty of good used caravans for sale.
Take a small torch when you inspect the caravan which you must do before parting with any money at all. Look under bed boxes and in cupboards (especially under the sink) for signs of damp or water ingress with tell tale black mould, bubbling or discolouration of wallboards. Look in the interior front and rear corners and inside the front locker where the grab handles are fitted to the outside and check inside along the line where the awning rail is fitted. Check the curtain linings, black mould can sometimes be seen on or behind curtains and blinds. Pull down the edges of window rubbers slightly to look for black gunge, water, green algae etc.
The tyres may need changing although the tread pattern could look ok, because the sidewalls begin to deteriorate after 5- 7 years so budget for tyres (deduct from the asking price) unless there are recent receipts for replacement tyres available for inspection.
Good Luck and if you have any queries don't hesitate to ask