No worries, I just check itch.io frequently for news, so I usually see your messages quickly (also get email notifications, anyways).
I did a search for the plugin, and I couldn't find it. The closer I got was this, which doesn't have the merchant's cash, but has a stock system.
There's many ways to approach GameDev, I just focus on whatever I feel like doing since it's a hobby for now. In any case, I'm now trying to learn more before resuming development.
I've also just found out that there's a new engine that'll be released soon, RPG Maker MZ. You should take a look at it. It seems to be addressing some shortcomings of the MV version, although there isn't a lot on info yet.