Event-based analytics package that won't break the bank with high volume

I'm using an application that is very i开发者_运维知识库nteractive and is now at the point of requiring a real analytics solution. We generate roughly 2.5-3 million events per month (and growing), and would like to build reports to analyze cohorts of users, funneling, etc. The reports are standard enough that it would seem feasible to use an existing service.

However, given the volume of data I am worried that the costs of using a hosted analytics solution like MixPanel will become very expensive very quickly. I've also looked into building a traditional star-schema data warehouse with offline background processes (I know very little about data warehousing).

This is a Ruby application with a PostgreSQL backend.

What are my options, both build and buy, to answer such questions?

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Why not building your own?

Check this open source project as an exemple:

http://www.warefeed.com

It is very basic and you will have to built datamart feature you will need in your case