Strangely these are sought after (probably because they leaked and/or got lost/thrown away and are usually missing). They normally go for £5- 10, though this is a nice example. The rush to bid is rather revealing as to the item's value.
As to Kitmaster kits, the rarer ones (BP for example) fetch good prices. and it must be remembered that the dearer ones where over £10 in today's money. It's probable that the emphasis on these dearer models led to their demise. I, for one, didn't have 10/6d to spend on the latest loco kit every month.