Thank you to everyone who replied.... I really do appreciate the feedback, I wish I could buy all of the rulers, but like so many people these days, I have to watch my nickels (no more pennies in Canada). Lots of great advice, as always.
I do not have a Joann's where I live and until I read that post never even thought about checking for rulers at Michael's. Locally, my options are a small quilt shop, a national fabric store and a Michaels. I checked out the selection at Michaels and think I may wait for the 50% off coupon and get the 12 1/2 inch (or maybe get 2 coupons and buy a second smaller one too). I have not made blocks that large but looked thru my wish list of quilts to do and there are 2 that have larger blocks.
Thanks again