In case anyone else is interested, I found boxes of 50 plain white matchbooks at the Smart & Final in South San Francisco! And they only cost $1.15 a box, way better than the $16.00 for 50 they were charging at some wedding favor websites. I bought 6 boxes, and look how cute the packaging is:
There is some tiny writing at the bottom of the books that says "D.D. Bean & Sons Jaffrey, N.H.", but it doesn't stand out at all. Hope others can use this info in the future. Thanks for reading!