Nothing like virgin film holders, especially ones older than your mother.
I bought a couple boxes of 2 1/4 x 3 1/4 a couple years ago off EBay and was pleasantly surprised that they were indeed... unused.
Just as happy with a set of 5x7s that had writing on the film memo area but looked brand new... used once I guess. Those were around 10 bucks a piece and absolutely clean.
Take good care of them, they will last forever.
tim in san jose