Gents, I need your advice. I have been approached by someone who has a Collins manufactured R390A/URR for sale. The tag says "Collins Radio Company, Order # 8719-P-55". Serial number is 3605. The radio looks super clean and it comes with a spare tube set, including two 3TF7's. What is a fair price for this thing ? I'm not sure that I'll take it at this point but I'm thinking about it. Thanks Phil