I forgot to thank you for all the work you put in tracing out that circuit. It's interesting and nice to have.
I was just at Fry's a little while ago. They had a cheaper CM preamp ($30) I hadn't seen before. It has a gain of 13 dB, if I recall correctly, and a noise figure of 3.5 dB. The single 300-ohm input is via a thick, heavy-duty, captive balanced line a couple feet long that terminates in large spade lugs. The injector is a small satellite type with a cable shrink-wrapped at the power socket. The cable runs to a wall wart.
The more familiar CM preamp (I forget the number now but it's been discussed here) was $60.