We have an API for the SA44B that allows it to be used with a Raspberry Pi 2 (and probably on newer versions as well). It is kind of hobbled in this mode, but you can do some basic sweeps and probably even stream 40 kHz of decimated I/Q if you wish. You would be responsible for the software though.
For using Spike, an Intel NUC running Windows can be useful if size is a concern.