I have built up a collection of 6SN7 Tubes to try out in my ALO Studio Six, they have all been purchased from Andy Bowman Vintage Tube Supplies in the US. He has a legendary reputation for quality tubes. I have the original invoices with descriptions.
All valves have the original boxes.
KEN-RAD 6SN7GT/VT-231 - Nice new, very low Mic. Del. 1940's unit staggered plates, rare tube - $76 US
RCA 6SN7GT Grey Glass Nice, new, very low Mic, Phono input sel quality (green) 1940's - $116
RCA 6SN7-GT Grey Glass, new, Perfect Micro Mirror balanced half's of unit, 1940's WW-2 era, Phono input sel (green) - $86
Will accept PayPal, sorry no trades, postage additional to overseas buyers I am in Australia