You'll have to look for what's out there. Our posts are 0.5" holes on 0.75" centers, and this is a pretty common layout. Having said that, a lot of the posts with more metal in them that will grip spades more tightly use their own proprietary chassis holes, so it gets tough to find what you're looking for outside of Cardas.
The general lack of posts like this made me move away from spades and back to banana plugs long ago.