Hey Margo, I reckon that you could use the Cutting edge strips to make your own Add-a-quarter or eighth ruler as well
Just been looking for their availability in UK and found them here
http://www.creativegrids.com/acatalog/info_TCE001.html and since the strips are 3/8" wide, I can have a go at cutting one down to give me the the 1/4" & 1/8" for the add-a bit rulers (I also have a retired 6" x 12" ruler - the markings have all but gone - that I could get DH to cut in two for a couple of dedicated rulers for the job too, at half the price and re-cycling something I already have.
)