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

No no, couldn't have that, would be a shame

a helicopter crash in a populated area has a high likelihood of collateral damage

Dune sand walking

To ad to others that already commented:
Brutal colonialism and imperialism, Hawaii, Guam, Puerto Rico, the Philippines to name only a few.

They'd come kill you for that.

Threatened? So they didn't ID them.

they're already on the verge of it, may as well hang for a sheep

This simply isn't true. When well piloted and maintained, an helicopter is a safe and sound machine, not a LoonyTunes gag.

Less safe than driving per mile traveled, which is arguably not very safe.

A pixel 6a is a good idea as the other commenter said but depending on what you're after you could get a fairly cheap second hand Samsung for about the same price.

That has the advantage of legitimately looking like it might actually be your phone that you've had for some time. In the same manner you could also get an old iPhone. It'll have a cracked screen because every iPhone older than 6 months has a cracked screen but the whole point is to be an unattractive decoy, you want the most average boring looking phone possible so there's nothing for them to be suspicious about.

Was it Biden? Obama?