Graphene OS drops support for devices pretty soon after Google does. It’s not a good idea to buy anything before Pixel 6 to run Graphene OS right now (see https://grapheneos.org/faq#supported-devices)
This will get better going forward since Google is supporting the Pixel phones for much longer (5 years for the Pixel 6/6a onward, 7 years for the newest devices).
They are not hard to acquire, and they only have an “unreasonable price” if they are recent models.
You won’t have any trouble finding a second-hand Pixel 5.
I recently bought a Pixel 4a at 120€ / 131$
Graphene OS drops support for devices pretty soon after Google does. It’s not a good idea to buy anything before Pixel 6 to run Graphene OS right now (see https://grapheneos.org/faq#supported-devices)
This will get better going forward since Google is supporting the Pixel phones for much longer (5 years for the Pixel 6/6a onward, 7 years for the newest devices).