Wonder how much it takes to run the coli
On a single VPS with 12-16 cores and 16GB of ram, you're looking at 150 to 300/month depending on the provider. You can do it with a lot less, but the hardware is there for spikes when shyt happens.
Most bulletin software is coded in PHP. PHP is CPU intensive while the database is more memory intensive than CPU intensive although it can be CPU intensive depending on the complexity of the queries.
You can "cheat" with a bunch of cheap $5 VPS running a PHP-FPM farm doing the work with Nginx or Apache sitting in the front spitting out the HTML, use micro-caching for the pages (1 second page cache times), and having the folder holding the bulletin shared on a clustered filesystem like GlusterFS. Run the database on separate VPS connected on a private IP. You won't need as much CPU power but enough RAM to hold the entire database, buffers, etc..