About the cost, I bought a demo from the factory, new in appearance and functionality and with a 1-year warranty, for about half the retail price. See "Second hand market" on the Sonosax home page. Dealt directly (in English) with Mr. Pierre Blanc in a smooth and easy transaction. As I recall, shipping to USA took four or five days.
I've used it only a few times but am happy with the results. Controls are minimal, such as the 3-position switches for headphone volume and gain. I don't think the fader knob adds any gain, just attenuation from the selected level (20, 46 or 72 dB) down to -inf. I like the idea of using it with the ZFR100 (not an option for me at the moment), but to use it with other tiny recorders for maximum minimalism, the SX-BD1's line out signal is true line level so too hot for some consumer decks unless you use a pad, but it can be set to mic-level output. Besides use on a boom pole, it attaches nicely to c-stands, etc. and offers a lot of clean gain with a long lasting self-contained power supply for many odd situations.
With batteries, mine weighs 5.6 oz (158 g).