Mark, I've bought cheap ebay before and they lasted about a year but were cheap enough to keep replacing.
Later in your post the price is £29.95 which sounds more likely - I've since bought genuine BMW stock and they are different and have lasted far longer . . . .
I would certainly say go for the ones - like the ones pictured - with a lot of lugs. Whilst mine still look good the really. cheap ones I bought really don't grip well. They don't fall out, but they do revolve. A good job that I am not obsessive about the caps aligning with the ///M badges!