I’m not sure if Patreon will take cent pledges. If they do, I don’t see why it wouldn’t work. Though just to point out, it’s not 500$, it’s 120$.
You can also try to sign up for Patreon’s beta program with annual memberships. I wouldn’t hope for anything though, I would be surprised if they still even checked the form submissions.
Is there a reason they need to use Patreon though? Until annual subscriptions come out for everyone, they’ll have to do this all again a year later, assuming they’ll remember. A one-off payment elsewhere might be better. And if you lock certain posts to higher tiers, they’ll never see them anyway. (Since they’ll be pledged too low.)
The issue here is that if they cancel their pledge after, they will lose access to your patreon. You have to use the annual plan patreon provides (as mentioned, isnt released for everyone yet), for it to give them access for a year. A single pledge, will just be counted as a single months pledge without using thier annual system.