Hello! I ran into the same dilemma with trying to find fabric. I raided my local Joann's (which had only a handful of plaids in the whole store D
and couldn't find anything, so I decided to search online and I found this:
It's not the perfect match, but it's the closest thing I could find in days of raiding the internet.
I ordered it and it came in about a week. It's uniform fabric, so it's thick, but nothing an average sewing machine shouldn't be able to handle. I haven't sewed with it yet (I'm out of muslin and can't do my mock up D: ) so I can't really give any advice on that end, but I can't imagine why there'd be a problem.
And as for customer service, this was my first time ordering from there, but my aunt orders fabric from there all the time and has never had a problem, not to mention there shipping was rather speedy (they ship out of Pennsylvania I believe, and I live in Georgia, so it might be longer for someone further west).
I hope this helped! And sorry if I rambled. I just finished a Chemistry Essay and my brain's a little fried.
Oh! One more thing! The website doesn't say, but I measured the plaid rectangles and the blue rectangles are about 1 1/4 by 1 1/2 inches. The pure white rectangles are 7/8 by 1 1/8 inch.