This has been a huge drain on the finances of the Planetary Society. I thought the $4M might have been an exaggeration, but nope. A perusal of the annual reports shows they really did spend it, or at least allocated it to that accounting bucket.
That's bloody cheap for three missions, and believe it or not they may have decided not to include something like an external watchdog timer due to the weight, every gram counts on launches. And it could have been worse, they could have mixed up inches and centimeter, but I guess no one spending millions would ever do that :p
Cheap for big space for sure. For microsats, not so much. AMSAT (who probably has launched more microsats than any other single entity) estimates launch costs at $100K USD/kg. So, I could see a $250K launch bill x 3. Maybe tracking station time is more expensive than I think it is. But over $5M for three microsats really seems expensive.
For reference, a 16 pin DIP package is approximately 0.001661 kg. So, we're talking about a sub-$300 decision with solder and support components. Not cheap, but reasonable insurance in light of the launch costs.
Regardless, testing adds no weight at all.
The good part of all this is that it has me reading up on microsats and might get inspired to get my HAM license and join AMSAT. Those folks really have cost-effective space nailed down.