Just wanted to inform you of my experience with the buyer gamebrickstore (Andrea Gasparrini) on eBay. I sold him a Casio OR-264 64kB RAM cartridge after he begged me several times to reduce the price. After the sale there was already a messagee to inform me to pack it well so it would not be damaged (I should have known better at that point). I sent the package either way and of course it arrived in good order, he then told me he was unable to load Nemesis from tape into the RAM of his MSX (64kB HX-10) combined with the 64kB RAM in the OR-264. He later filed a return on the basis of item being defective because it did not respond to mapper OUT commands (which is of course totally as expected).
Obviously eBay being what it is it favours buyers over sellers so the return was of course accepted even though he did not respond any more to any of my messages.
So this is just my story as a word of warning and you should do with it however you feel appropriate.