The problem with WBAC is, if they have offered you £300 blind - then when they see it - expect them to amend that offer down to about £20. They are, and will be brutal.
I have a firm belief that most driveable(ish) cars will sell for near enough £500 on ebay, which has held true for the last 3/4 sheds I have sold for my dad, including a Jag with a hole through one cylinder. Almost every time it has been a chap from the eastern block. One guy i was speaking to said, he does the minimum required work and then takes the car back home to sell. Apparently even a shagged BMW/VW/Volvo/Jag will catch 1-2k in Latvia. Not sure how true it all is, but he still texts me every now and then asking if I have any old cars