Chameleon coating. bodx1,000 = 2k
ECM. Rx1,000 = 1-10k
Improved Sensor array. 1,000
Those are the three best for a flyspy. The coating will give a bigger negative to being noticed so it really isn't needed. The ECM and Sensor array will help it get information and not have it being tracked back. The flyspy's cost 2k, so if you add in the sensors you are paying 3k per and can send out more to get the job done. A dozen eyes that may be seen are worth more than 5 that are really REALLY hard to see.