Nice article. Other than open source, one more affordable option available today is SAAS BI. Especially for small and medium companies who may not want to allocate precious IT resources for installing and maintaining the open source solutions in-house. I work for Zoho and we have one such SAAS BI solution, Zoho Reports (http://reports.zoho.com). Do have a look.
Zoho Sheet (http://sheet.zoho.com) and Zoho Reports (http://reports.zoho.com) have pivot tables since 2008. While Zoho Sheet can support 1 million cells, Zoho Reports has customers having 15-20 million rows.
I don't work for Zoho, and I'll echo the support here. Zoho's product suite is great. As a user, I really like the way their product tie into each other. Have built a number of internal corporate projects on Zoho and have been quite happy. Customer support is surprisingly good too, and willing to do custom stuff like create special billing for our purposes that don't fit their normal pricing.
Tried Zoho Creator (http://www.zoho.com/creator) and its reporting partner Zoho Reports (http://reports.zoho.com)?
Disclaimer: I work for Zoho