Looks like we may soon be getting more things to buy using samples and requisition slips. The Catalog Expansion has no cost, and buying it does nothing. The Upgrade Effect text must be null for Catalog Expansion, that field just shows the effect for whichever upgrade was previously selected.
Edit: It's been acknowledged on the official Discord, looks like it's unintended:
ALERT: ROGUE ITEM DETECTED. The Ministry of Truth has confirmation that a rogue item called the "catalog expansion" is temporarily visible in the Ship Management menu and, in accordance with regulations, we instruct all Helldivers to avoid this rogue item until further notice. The Ministry of Truth cannot confirm the reliability or safety of this item, nor can they confirm its origin.
I attempted to buy it, but it wouldn't let me.