Campaign Effectiveness/Costs

So... how effective are these campaigns, and what are the costs per applicant?

Over the last 2 years Castablasta campaigns have had an average open rate of over 50% and a clickthrough rate of  30%

The stats below are based on campaigns (sent at the start or during a casting), and cover a broad range of productions from the most popular reality shows (Block/MasterChef/etc) to the more obscure and difficult to cast shows (You can't ask that/Catalyst/etc).