Is this for an M-car?
I think Frank @ Drivers Edge Autosport (in the building beside Open Road Audi) has Redline 10W60. I don't know how much he sells it for but he's always had the best prices in town (in my experience anyway.)
http://www.driversedgeautosport.com/redline_10w60.html Edit: $11.49/L. Not bad.
If you're looking for Castrol TWS/Edge, unfortunately I don't know anybody who sells it in a 10W60 variety as it's a very specific grade of oil. Lordco might carry a 10W60 by Liquimoly but it will either be expensive or not readily available.