I *tried* to buy rulers locally but could only find one straight ruler out of all of the local quilt shops & sewing machine dealers - I guess there's not a big demand for these in my area!
I've bought a couple basic ones on Amazon (mostly Handi Quilter brand), but I've been restraining myself as I'm going to a big quilt festival in about 2 weeks and I know there's at least one booth there every year selling tons of different longarm ruler/templates. I just got my longarm a couple months ago and have funds set aside to do a little bit of splurging in that booth this year.
(Not sure what brand they are, though.)
I did buy the Westalee feather template set while I was in the Portland area on vacation recently - spotted it in a LQS on sale and couldn't resist. Portland seems to be a great place for quilters, I found so many great shops out there!