This is a stub for the effort estimation methodologies useful for a SSIS development project.
Estimation methodologies for SSIS in particular or Business Intelligence in general can vary based on the size, complexity of the project.
Books related to effort estimation methodologies in general or SSIS/BI in particular. Add books' link here.
Articles related to effort estimation methodologies in general or SSIS/BI in particular. DTS to SSIS Conversion Effort Estimate Excel Workboook. It can be used for new SSIS development too. http://aalamrangi.wordpress.com/2012/03/20/dts-to-ssis-conversion-effort-estimate-workbook/
SSIS Design Patterns Wiki http://social.technet.microsoft.com/wiki/contents/articles/10844.ssis-design-patterns.aspx
Aalam Rangi edited Revision 2. Comment: Fixed typo for "vary".