cost of SOA Imlementation and enterprise architect consultancy ?

I am running a finance based company with 750 employee and around 10-15 departments including hr, finance, operation, sales, marketing, admin etc. My company is process drivan company. I have purchased some indepent softwares for managing my company and process.
But now I want to consult some one for SOA implementation and Enterprise architecture consulting for better manage my IT plateform.
Can any one tell me the cost of these services and open source tools for that ?