This is true - I am also a BVWS member - their monthly magazine, The Bulletin, is a beautiful publication with excellent production standards.
The BVWS do not sell spares for radios (they sort of do - they sell modern capacitors to replace those in valve radios & TVs). They do have a facility where members only can for free put in a For Sale/Wanted small add in the next copy of the Bulletin, but that takes weeks or months, has a limited readership and is members only.
The UKVRR site mentioned is by far the biggest & most active site of its type I know of in the UK - GVR (where I'm also a moderator) is far smaller but the folk there are very helpful too - most are members of both fora anyway. As the Bush radios are very common (250,000 Bush DAC 90As alone were made) and restoring them is popular, I would suggest UKVRR as the best bet.
Nick