I'd have the dealer fix it free under warranty. $700 is inexcusable. Parts are cheap.
If you do it yourself, get the special socket, and just order new seals from the dealer... they should be the good stuff. Torque procedure is 30Nm, release, 30Nm, release, and then 30+5 Nm final torque. Don't take my word for it though, read it in the procedure from the factory OM606 manual:
Edit: Corrected link.
http://www.w124performance.com/service/w124CD1/Program/Engine/605_606/07.1-8627.pdf
