I was delighted to find these "yardstrips" (my name for them) from ACE Hardware. They are tear-off paper rulers, 90 cm long, hanging from a card in batches of 100. Perhaps about $6. A few cents per ruler! Great for kids, though with some paper-cut potential.
They come out of the box rather curvey, so you might allow time to hang them up for straightening.
My local ACE/Tags hangs them in the tubing section so customers can measure out lengths of tubing. I gather they dont often sell them, as they were unprepared for someone asking to buy a full card. I had to call the next day, be called back with a price quote, and then go back to the store to pick them up. They were quite startled someone might want 5 cards (ie 500 paper rulers). Sigh.
The card says "ACE ACE - Shopping is easier at ACE - Please take one".
Reorder #9004144
I paid $6 each, $30 for a box of 5.
But the pricing process was informal and fuzzy, so you might push.
There was earlier talk of giving me one for free, or for one dollar.
ACE sells through distributors. Most are local hardware stores. Some are online. But I haven't yet seen an online way to order this part.