BBA Reman have the Espace BII unit (body control module as they call it) listed as one of the components they can repair/remanufacture.
http://www.bba-reman.com/content.aspx?content=Renault_espace_body_controller_failingAs they fix your existing unit the immobiliser code and keys are not an issue as Tom has pointed out would be the case with one salvaged from another vehicle. On reinstallation it would however still require reconfiguring by a dealer or automotive technician that has a Renault CLIP system but at least it should work out much cheaper than a complete new unit.
Martin