There are, also, some mini pci express ssd no msata (but with built-in sata bus).
For example, it is the case for all asus eeepc ssd :http://www.ebay.com/bhp/eee-pc-ssd
But, these ssd are not very fast.
However this Super-Talent sdd is better I think: https://www.amazon.com/SUPER-FMT256JCRM-Super-Talent-256GB/dp/B017O21IPW
And it, also, exists in 64 and 128GB.
The Espressobin provides a mini pci express 1x interface, but I don’t know the revision (1.0, 2.0, … )
So, can something prevent these ssd to work with the Espressobin, except for a problem with the disk linux driver(if not ahci) ?