I just posted ads on Prefired and Airsofthub last week for the first time in many years, got a few e-mails with very similar wording essentially trying the exact same thing. If you're new to/not familiar with the site in question they can be somewhat convincing, and they English was actually correct in the e-mails I received. Of course the message coming in the wrapper of a normal DM is the main giveaway but I wouldn't blame people for falling for it if they're new to a given site.
I'd say I'm surprised at these scammers becoming so active on niche little airsoft sites within the last year or so, but I'm sure it's happening in all hobbies and areas of interest where folks commonly do online buying and selling.