Hard disks are sold in fake GB/TB ( where 1 kb = 1,000 bytes instead of 1,024 bytes) so I'll use those numbers. Based on that screenshot, 1 zap uses around 1kb (1,000 bytes) of storage. 1GB = 1,000,000 KB. According to Backblaze (https://www.backblaze.com/blog/hard-drive-cost-per-gigabyte/) storage costs are around $0.015 per GB at the end of 2022. That works out to $0.015 / 1,000,000 KB = $0.0000000015 per KB or Zap. Moscow time (Satoshi per Dollar) is currently 3285, so the price of storage for zaps in sats is $0.000049275 per zap. This does not include the storage space for the lightning transaction itsels, however it's cheap enough that a single sat zap is economical in terms of storage.

TL;DR

Storage costs are negligable. Zap away!