We got a decent Swift Challnger 1992 5 berth with all the mod cons for £1900.00 from ebay so its perfectly possible to get a van for your budget, just need to check for damp of course but you need to do that with every van not just the older ones.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.