Hi Foreign,
There is another alternative that I have happily used for the last year and a half - 6N6P gold grid tubes. To me these sound better than the stock 6N6P-i. The sound is more mellow and they have a beneficial effect on driver tubes that are skewed towards treble by toning them down a little. (BTW, the gold grid was invented by GE and used in their 5 Star extra long life tubes. However, nobody bothers to mention this.)
The best deals on Ebay for the Russian tubes seem to be 4 tubes for $18 including shipping ($17 for 2 tubes). The general consensus is to avoid Russian tubes made after 1983 since it seems that the quality started to decline. Ask the vendor what year the tubes were made. This does not apply to the Electro Harmonix tubes which are currently in production and not NOS.
I finally caved in a bought a pair of 6N6P-IR tubes, but they have not arrived yet. Shipping from Russia can take four weeks or more. I do not have experience with Electro Harmonix and DR tubes.