If it helps, I built an betatest onion for Wikipedia and all(?) the Wikimedia Foundation websites using EOTK* a few months ago, and documented the build process at:
https://github.com/alecmuffett/eotk/blob/master/docs.d/RUNBOOK.md
A basic test onion takes about 5..10 minutes to set up on Ubuntu or OSX/Homebrew.
A scalable full production loadbalanced deployment on some kind of cloud or server(s) should take a day or two, plus time to buy an Onion SSL Certificate where appropriate.
- alec
* Enterprise Onion Toolkit