Ok, so know how when you get a message you can set it to ding? Well my suggestion is for that to happen with shops. If you have a huge mall, it could be annoying. But with small shops or manual payments coming in, this could be useful! (I won't forget the poll this time)
You already get a message in chat when someone buys or sells to you, I don't see a need for it to ding as well. Plus, if someone spam bought or sold to you, I think the dings would get annoying.
Exactly the reason that it would be a /ps setting just like messages. If someone spams you in messages, it spams dings. But if someone sells promos to me, I like to thank them. But sometimes I miss it because I'm on the forums.
If you miss the message, you can check your rupee history. Since you said you were on the forums anyway.