More hardware isn't always the solution, but in this case it might be. Altough it better be combined with an upstream provider (or a good network admin) who knows and has the equipment to handle this.
I've set up quite a few clusters these days, and the database part is the hardest. Especially MySQL in multi-master setup is a crime. Postgres is a breeze nowdays (>9.1) with the WAL replication. Also, HAProxy is hard and Corosync/pacemaker between HAProxy is also not that difficult...
If they need help they can contact me