I got them off Fleabay 50 for £4.50 inclusive of P&P

What's the idea behind them Pete? Do they just make the buttons easier to push, or do they provide a degree of protection as well?
They are just a standard furniture product that someone is making out are for a specific detector and so have hyped the price. My link just informs others of that and gives an alternative choice. Glad you got what you wanted, that's the main thing.
It seems that some people find buttons on certain detectors difficult to press. I guess that these raise the buttons making them easier to locate and also prevent surface wear. Horses for courses!