There was a thread about XY tables recently - just saw this on eBay:which is an XY vice. They call it a two-way machine vice.
It's only 3 inch size, and it isn't exactly a piece of precision engineering
- but it's only £25.50 delivered, which is a whole lot less than a Proxxon or Wolfcraft.
Might perhaps be a starting point for those into improving tools - it looks like it needs a lot of improvement!
There seems to be several available. Usual disclaimer, but I'm not even a customer.