Any software defined radio that can transmit on these bands and RF amplifiers.

The ham radio community also has all the information on how to build them out of of basic components, power RF transistors being the most expensive components, but that is still dollars not tens of dollars.

Sometimes ready made gps jammers can be obtained off the shelf from overseas markets outside of the hegemon's reach. But active protest does require being smart about it. No point in just causing irritation with the population while leaving the enemy able to operate unencumbered. That means performing observation, OSINT, signals intelligence to understand their system and find their weaknesses.

They will have covered most vulnerabilities from their own guerilla warfare manuals so study those and find their blind spots. Find where they have become overconfident in their hardware's ability. Where they have started taking from granted technologies that remain only reliable in peacetime.

Use their systems against them