Options:

- datacoin has very cheap rates.  Its hashrate is low and there is no easy automatable interface, but it's pay-once.  It's designed for small-medium data.

- bitcoinsv stn is pay-once and is designed for gigabytes of data.  Uploading may require running a full node

- a pay-monthly blockchain like sia or filecoin could be forked to change its behavior to pay-once

- others? ethereum has storage now, haven't looked at it recently