I have never seen an item there :/

I could be wrong about this (haven't been on Subeta very long) but I think the staff only stock items in the Free Shop during special events (like a Luminaire giveaway). I've never seen anything in there yet, even though the 'restocked now!' line appears frequently enough. it would be nice if there was a subtitle like 'the free shop is closed!' or something.

The free shop gets stocked occasionally, and there will be an announcement in the news when they put items in. When it is stocked, everything will show up as 0sp, and the item images will all be the same, so you don't know what you're getting.