The message I get is a light warship and 5 merchants for $75 and +1% inflation. The warship is not much of a factor and the inflation can be countered with other decisions. So, 5 merchants for $75 is one merchant for $15. A merchant in the Atlantic Shipping box earns approximately $2 or the equivalent 2 WS, or one of each per turn, determined by the AI. Thus, the merchant will pay for itself in 8 turns or so. If the message you refer to has the same ratio, then it's worth it IMHO. Good luck!
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