I can attest that Swappa is awesome, as is GrapheneOS. GrapheneOS now supports Google Play Services and so it should be able to run WhatsApp and any other app that requires those services be installed.

As for the bigger question about money and privacy in general, it's possible to get a lot of privacy for not a lot of money.

For example, riseup provides email and VPN service in exchange for donations. https://riseup.net/

It's often fairly simple things that can make a big difference. In my opinion, the biggest problem is that it's takes time to learn what protections are actually effective versus who is just trying to sell you something.

For what it's worth from a total stranger on the internet, I can say TheNewOil really hits a home run on that front. It's not aimed at "privacy at all costs" people. It's aimed at people who just want a reasonable amount of privacy online. You can spend a few minutes watching a video and then set up something to make you a little safer online. Do that a few times and you'll be in a much better situation.