Volvo built-in satnav - replacement kit?

Does anyone do a kit to replace the Volvo built-in satnav with a sensible one from somebody else? It's a nice bit of kit when it works but hideously expensive when it doesn't.

The original one is quite large, pops out of a hole in the dash and since thieves will not be able to use it in any other car, it's not attractive. I'm just thinking there must be a way to fit a more accessible replacement.