I buy and sell them regularly and they sell just fine.
Another great thing about PCs is that some collectors [me included] are happy to buy cards that have been written on and mailed. I like the time capsule effect of it--adds character. The fact that under the grading regimes the cards are poor or fair is just a money-saving bonus. All of these would grade poor or fair at best but I'd rather have them than unused near mint versions, even signed:
1949 mailing date:
Mailed from Brooklyn in 1957:
Signed and mailed while Paige was on the team:
Or this 1958:
