I would suggest a service such as this one:
https://www.ovh.com/ca/en/cloud/stor...ct-storage.xml
(Amazon Glacier is another good one (
https://aws.amazon.com/glacier/pricing/?nc1=h_ls).)
No need for full servers costing 5-10x the cost to do backups. And you wouldn't get replication, file durability and the same security level on a server that does other things than backups.
I have scripts ready for full servers, vhosts and database backups. Contact me.