I occassionally order cloth from Strathmore and find their fabric to be of a good quality. My only beef is that they do they have a large 11 oz range of tartans and a smaller range of 13 oz tartans, but don't do any 16 oz from stock -- all custom in that weight.

But I've worked with some of their 13 oz cloth and find it to be very good quality.

What tartan is it you are interested in? If you like, you can order a swatch from them off of our page:
http://giftshop.scottishtartans.org/material.html