I'm afraid I have no better advice than, "search your favourite auction sites" or try a request on the Marketplace forum.
Originally Posted by Lispy
One other suggestion as these devices start to wear, is that if you can remove the coil and add it to a different phone, you could also measure / scan the part and get it 3D printed - then install the coil into it. If the part is still in one piece or can be stuck together long enough, you could also go old style, make a mould and cast a new one.
Some people have made I think coloured screen surrounds for the Pre3 and new magnetic headphone adapters for the Veer.
3D printing is a more expensive option that finding a phone back to buy, but it is an option.