Database reporting alerts I am about to make a reporting/alerting mechanism that will periodically examine state of one of my databases that is constantly updated and send reports/fire alerts if needed depending on the data in the tables.

I am not familiar with MS BI stack. I played a bit with reporting services but as far as I can see it can only send periodic reports. I need some quite moderately simple logic before sending a report that will decide whether the report needs to be sent at all.

Should I go with custom external solution, some core SQL Server stuff (triggers + CLR support?) or there is an existing tool in BI stack that will suit my needs?
Depends on how sophisticated you want your reports to be.

The simple solution is to create SQL stored procedures that generate emails with reports as embedded/attached HTML or as attached csv files.

The stored procdure can be called from SQL Agent using the flexible scheduling and error reporting that is already built in.