Of course they cost money. Clearly they also cost less money than a cruise missile. maybe you're thinking of Reaper-style drones? These won't be like that, they'll be closer to the Switchblade [1] which is now being sent to Ukraine. Those are single-use "kamikaze" drones for use on the battlefield, the seaworthy version would be similar. The article does not mention the unit cost other than stating it is "less than anti-tank missiles like the Javelin".
Indeed that's very cheap and single-use is a no-brainer. The firepower isn't great though ( "equivalent to a 40mm grenade"), especially in a naval engagement ( the original discussion). You'd need more than that to sink an aircraft carrier; however if the idea is just to render temporarily inoperable, well targeted strikes ( against an aircraft carrier deck, a frigate/destroyer radar/missile launcher) could be enough-ish.
That is the Switchblade 300, I assume something more akin to the Switchblade 600 [1] would be used for which I can not find any price information other than it being "cheaper than a Javelin". It seems the US Navy has already show interest, albeit for use by surface units:
On 31 March 2021, AeroVironment was awarded a USD26.1 million contract by SOCOM for the Switchblade 600. The system addresses the United States Naval Special Warfare Command's Maritime Precision Engagement (MPE) requirement to engage asymmetric threats with Combatant Craft Medium (CCM) and Heavy (CCH) boats acting as host platforms.
[1] https://wikiless.org/wiki/AeroVironment_Switchblade