What if he he/she doesn't want a hand crank? We all have our biases. There are things that really interest us. For some, it's the development of the sewing machine (Steve). For others, it's the hand crank machines (Leon). I like mid century machines. Some people are really into treadles. Some people like what's old. Some people like Brother sewing machines (Cari). Everyone has their favorites.
Although I bought a hand crank yesterday, I have no desire to keep it. I figured I'd find a home for it, and it wouldn't go to the metal recycling center.
I would suggest that we encourage people to get and keep sewing machines that they enjoy whether they are red featherweights or 15-91s with 15-88 faceplates. There are more than enough to go around. No matter how many we manage to save, hundreds more will go to the recycle center or the dump. We can't save them all.
No one collects 15-88s, unless they have some special emblem. There is nothing special about them. The technology is not interesting. If you like 15s, you probably want a 15-91 (or have two or three). I think he/she ought to do what they want to do and try to sell the 15-88 with the striated plate, or donate it, or recycle it.
JMHO
bkay