What are used tubes worth ?


My ARC VT100 blew one output tube (the filament opened) so I replaced the entire octet.
So, I have seven 6550 output tubes that work fine, and have probably 800 to 1000 hours on them. They are the original tubes that came with the amp.
Any idea what they might be worth ?
Thanks.
mabonn
Thanks Rodman99999. I will contact tctubes to inquire about testing.
Does anybody know anyone in the San Diego area who can test them?
@Mr M- You're welcome. There is probably a musical instrument/amp repair shop, in your area, that could help you with that. ie: You might try these guys: (http://www.keyboardservice.com/Organ_Repairs.asp) or (http://www.topgearguitar.com/tghome/)