I'm guessing the $50 range is one channel and no power supply? I'm doing a parts search today. I know I can build an inexpensive prototype. Maybe I should build both and see what I like best before I blow the money on black-gates and auricaps.
The thing holding me back right now is that I've been reading about how some people have had hum problems and also issues diving certain loads. I shouldn't have a problem with 100K input impedence of the power amps, but I am still hesitant about the hum issues. Several people on AA give advice about adding followers to the circuit and input buffers. That increases the complexity and I don't know jack about tube designs so I hesitate to just start cascading design blocks. OTOH, I know I can bang out that SS design in few hours, including the supply.
BTW, I got the second amp installed and I'm running a passive splitter from the PV14. It sounds great! It's incremental for sure, but there is noticably more power throughout. There is more authority in the bass region and more depth. I was hoping that the upper part would sound a little more clear. It seems that it does but not as much as I hoped. I think this is where going active will help. Now I need a few days alone with the stereo but the GF decided delay her visit to the parents so I won't be able push any limits while she's in the house. ;-)