Hi DonLuca,
dadong is absolutely right - if you want a good deal you have to be patient. If you take your time, you will find somebody who has the tubes you want and does not try to get a fortune for them.
Another valuable point is: Communicate. Ask questions from the seller. Some of these people do it as a sideline and hobby and like to hear from people. In several instances the seller threw in extra tubes in the sale after I told him that I have this little amp that only takes the 6AK5 "peanut" tubes and that I cannot really use the other 200 tubes he has for sale.
One gentleman that sold me several tubes told me that he restores old tube equipment and suggested that I try a tube that is an equivalent to the 6AK5. (A friend of his had told him that it would give better bass than the 6AK5.) This tube is called 6AJ5 which is an older tube than the 6AK5.
I asked David Zhe Zhe of Little Dot about it, but he said that he has no experience with it and cannot recommend it.
I kept on looking at the specs, which were almost identical to the 6AK5 with the same pin out. Another friend (a retired electronics engineer) thought that it would work, but based on the specs the gain would be a little lower, which just would mean that I would have to turn it up a little more. (Correct assessment)
I decided on looking for Tung Sol tubes since I only have good experiences with them. After a couple of weeks I found a seller that met my buying criteria; $8 for two tubes, including shipping. I popped in the tubes. Would the thing work? Explode? Don't worry, everything is fine.
The gold grid 6N6P sounded a little soft with these tubes, so I put in the OEM 6N6P-i power tubes. First impression is very positive: Nice fat bass, very good mid range and crystal highs. The sound is very nice and very listenable - will let you know further impressions when I have more time on these tubes.
So if the tube rolling bug bites you, you may want to give these a try. There are many US manufacturers that made these tubes. No $68 tubes here, because there is almost no market for these tubes.