NOS aircooled R jug, what's it worth??

[grundlegrabber]

I found a guy who has 2 or 3 NOS 250R jugs for the aircooled Rs. Not sure yet if they're 81-82 or 83-84. I'll find out soon. He says they have surface rust from years of shelf life, but they are otherwise new. I might pick them up to resell. What are they worth, anyone know? I don't wanna piss the guy off by lowballing him. Any input would be greatly appreciated.

[petesatc]

Well i have been looking for a NOS cylinder for over 2 years now....never seen one on ebay which makes it pretty hard to value them but if you do score them i would be VERY interested........