Can anyone here tell me what 50 round mags are going for?

[NearSightedSniper]

Subject line says it all.
Want to know the value of 50 round mags in good condition.
Thanks in advance.

 

[WCC]

They are like hen's teeth at present. We use to get the SADF ones for about $20-$30 in used but still good condition. I now often see them on Gunbroker for north of $100.