Have a look at local farm dispersal sales -
see:http://www.howkinsandharrison.co.uk/SalesDatesAndResults.aspx?id=4
You may be able to pick up a bargain.
Cattle trailers hold their value quite well, so the second-hand prices can seem high. When we were looking we decided to buy new and the dealers are always open to negotiation, never pay list price for anything.