99 tang - reciever sights

Whats up with the used flip up tang sights ,marbles - lyman, ect going for new prices on e bay, gunbroker, and auction arms ?
I type in savage 99 and these sights always seem to bring prices that are as much as new or even more ?
Some of the receiver sights seem to go for new prices also ?
Am I missing something ?

Supply and demand. The only new ones available are marbles and they are not as well constructed as the original style. The lyman 29 was offered new in 1903 for $2.50 as an option, but I think it is worth a tad more now.

Just a tad more than $2.50 ! ;D