This strikes me as a case where you vaguely perceived a problem, thought "hmm, personal problems are the best source of project ideas," and quickly rushed to create a solution because you're a maker who enjoys making things. Did you open a text editor alongside Slack, or message yourself/slackbot, and find both solutions wanting? Would you pay $1/user/month for the added benefit of your solution?

My rude, unsolicited, very possibly erroneous, but ultimately well-intentioned suggestion is that you release it as a free service and maybe open source it. If you brand it well you can collect some stars. But I can't see someone paying for this.