Anton Chuvakin wrote an article on the costs associated with Security Information & Event Management SIEM and log management which will help you decide whether you should do SIEM in-house or outsource to a Managed Security Services Provider. Anton breaks the costs down into the following categories:

• Hard costs
  • Initial costs
  • Ongoing operating costs
  • Periodic or occasional costs
• Soft costs
  • Initial costs
  • Ongoing operating costs
  • Periodic or occasional costs

BTW, in my experience, I have seen the total cost of a SIEM project (hard + soft) range from 10% of SIEM license costs (for shelfware SIEM “deployments”) to a mind-boggling 20x of license cost.