Jane's (extract available) reports that "four of Europe's leading submarine design houses have now all sought to craft compact, highly automated 'entry-level' submarine concepts specifically engineered to reduce capital cost and support overhead and manning requirements. As well as appealing to navies looking to acquire a submarine capability for the first time, the rival contractors are also eyeing nations that may be looking to recapitalise their existing submarine arms."
This is all because "The modern non-nuclear submarine is acknowledged to be a highly potent sea denial and intelligence gathering asset and, in the right hands, a very challenging adversary for even the best-equipped anti-submarine warfare (ASW) forces."
An example Jane's uses is the SMX-23, from French builder DCNS. It's a 900 ton, 18-person, coastal defense submarine that will only set back the buyer about $300M. The French are also offering the Marlin, an update to the Scorpene, while the Spanish are busy rolling out the S80.