This is that tabard.
I apologize for the lack of visual documentation. I did not take any pictures as I was doing it, only decided to make an instructable about it after I had finished it. If I make another one, Ill post pictures from that.
1st is the front, second is the backside. On the front, you can barely tell that the collar is a little lower on the front, and the seams on the edges come in right next to the black strips.
By the way, this tabard is entered in the Game.Life Contest! If you like it enough, please vote!
Step 1: Materials
The day I got the fabric I went to JoAnns. They had a sale on colored canvas that day, (and the fabric was 65" wide to begin with) so I was able to get enough fabric to make a couple tabards for around $10-15.
As for the amounts, you just need enough canvas to be cut into a 2x6.5ft rectangle (for the main body. 2x3.25ft on each side), and enough to make a 3/4" wide strip 4ft long. If you want to make a design in the middle (I have not yet done that), get enough for that too.