Well, the ones from Banditmania do come with fork preload spacers...
I had the Banditmania ones on my B12, but never bothered with installing the fork spacers. I only got rid of them when I went to a Hayabusa shock, since it lifted the tail with the stock dogbones as much as the Banditmania dogbones did with the stock shock - and I felt it would have been too much lift to have left the Banditmania dogbones in with the new shock.
One thing to consider... do you think you'd have any legal recourse from an ebay seller that sells you £7 dogbones if they break because they are substandardly made? We did have a member here that bought a used bike that had non-stock dogbones that broke. He wasn't injured, but under the wrong set of conditions, such a failure could be painful or deadly. IMHO, if you don't know what you're looking for or can't put trust in the ebay seller, you're better off spending the extra coin for a well known product.