I have all that stuff, this is not a practical matter.
It is possible to find chassis on ebay for around $500, like a PXIE-1062Q or 1071, but it's hit or miss, offered as parts since, I'm guessing, these sellers don't have reliable ways to test functionality. Tested, known good units are still above a thousand.
Controllers (CPU) are an even bigger problem. The cheapest solution is the PXIe-8379 thunderbolt remote controller. You can find these around $300. As far as I know these were never released fully to the public and they use Thunderbolt 2, which needs an adapter (Apple ~$50) to modern USB Type-C Thunderbolt 3 hosts and actually not many PCs work with them due to some legacy security feature. I bought an Intel NUC just for this purpose, and it sort of sees the device but not doing anything else. Out of 4 my old work Lenovo laptop was the only one that run just fine with it connected.
Embedded controllers are again go for above $1000 usually.
So if you add that together it's closer to 2 grand which is cost of doing business if the instrument itself is also 2 grand, but now you can buy those for 300 freaking dollars! And there are a bunch from multiple sellers.
The software is easy. The driver includes what NI calls "Soft Front Panels". These provide basic SA / SG functionality. The screenshot in my original post is from that.
Programming libraries are available freely for LabVIEW, CVI, Visual C\C++ and .NET.
The two things that are not possible without expensive, paid software is to have wireless standard measurements (e.g. LTE etc.) and to program the FPGA, because that needs a LabVIEW FPGA license. Latter one is a cool feature, but for general analyzer / generator use the default FPGA image has everything included.
What I'm trying to get to here is to have the board made cheap. Connectors are ~$20 apiece, so let's say total BOM cost is $100. Another $50-$100 is the PCIe extension cable, then the only other thing needed is a crappy old-ish PC to put this whole thing into. I'm planning on buying a refurbished Dell Optiplex for about $100, that has a full size 5.25" drive bay.
FYI:
https://www.ni.com/en-us/support/documentation/supplemental/12/the-ni-vector-signal-transceiver-hardware-architecture.html