Before I stopped fediverse, I was hosting lemmy on the cheapest hetzner ARM instance, with backups it was like 6€, so probably slightly below $7. Nextcloud has an ARM version so that would work.
Of course, only 40gb storage. I run nextcloud on an Intel VPS, it’s one of the few SSD + HDD offerings I’ve ever seen, and I got it on sale, so it’s less than 5€ paid yearly for 40GB + 500GB.