Prester John,

Yes, 13 oz. is a good medium weight wool for kilts.

Take a look at this website:
http://www.scottishclansman.com/Kilts.html

They sell a 4-yard kilt for around $250, and Clergy Green Ancient and Clergy Ancient are included in their tartan list.

I've had no experience with this company, but F16warbird said his kilt was made by this company.