I got my Funduino today -- it took 11 days. Still waiting for the DDS but I'm sure it'll be here way ahead of other stuff I need.
Interesting that the Funduino is marked as "Arduino" and "made in Italy". Oops.
Regarding plotting programs -- the gnuplot thing might be a good thing for my current lash-up, since I'm using a Raspberry Pi which is a native Linux board.
I've set my software to output to Data Analyzer 2003's "DAT" format if my file extension starts with a 'd', or CSV format otherwise. Data Analyzer will work with both actually, and Excel probably will too. The difference is that the DAT format uses a space delimiter while CSV uses commas, and for CSV I put in a header row of "frequency, dBm", which Data Analyzer isn't crazy about.
Also fooling with having the software find and report the frequency for peak response and guess I should also have it find the -3dB points. Fairly trivial except possibly if you have a plateau at either point and want to select the midpoint of that plateau. This is for crystal characterization, of course.