Where can I buy a base station on its own?

I bought a W52P and a W52H for the office, so there is one base station and two handsets. I want to take one home, so I need another base station. I can't find a model number for just the base station, nor can I find it anywhere, not even eBay or Amazon.

The Yealink and Gigaset base stations look very similar and I've seen some evidence to suggest that they might be interoperable?

Could someone point me in the right direction?