I use the Sylvania VT-231's in my BAT 150 SE's. I absolutely love them and they were a significant improvement over the stock Sovteks. I even collected a back up set.
Part of the reason I chose the Sylvania was based on the fact that they seem to be a bit more resadily available to purchase in groups of 4 or more which makes it much easier to collect a set of 12 than some of the other vintage tubes. I bought my sets a couple of years ago and, as far as I recollect, paid about $35-$40 a piece for them.
As far as the price now? - good luck!!
Part of the reason I chose the Sylvania was based on the fact that they seem to be a bit more resadily available to purchase in groups of 4 or more which makes it much easier to collect a set of 12 than some of the other vintage tubes. I bought my sets a couple of years ago and, as far as I recollect, paid about $35-$40 a piece for them.
As far as the price now? - good luck!!