CMS options for Weblogic Portal

Hi, I looking for some CMS options that can work well with Weblogic portal's Virtual Content Repository's.

I know interwoven's TeamSite works very well with WL VCR but We really need to some open source or economical CMS system.

I evaluated Alfresco doesn't have SPI library implemented.

I would appreciate if you guys can suggest some economical option for CMS that we can use for authoring contents and push/deploy in WLP VCR.

thanks!