^^^ The XLR1 has been discontinued and was in the neighborhood of $500 when it was available (maybe $450?). So difficult to find and pricey, especially for what it does. You can get a tinybox for 2/3 the cost and have a pre-amp too...
Yes, you are correct, the XLR-1 did seem expensive for what it does, i.e. power only. However, when you consider it more closely with respect to the M10 (and of course D1 and D50, and now also D100) it actually starts to make some sense. It has a number of positives, including physical attachment to the back of all 4 Sony PCM recorders for easy stealth operation, relatively small form factor (obviously not 'Tinybox small', but smaller than quite a few P48 preamps/power packs), balanced and locking inputs, P48 phantom power that lasts forever on 4xAA batteries (I've tested mine with my Beyer CK930's for 12 hours+ without the LED flashing, I just stopped the test at 12 hrs through sheer boredom), correct unbalancing of output, and last but not least, very clean super-quiet signal. Here's a link on the main M10 thread recently:
http://taperssection.com/index.php?topic=160902.msg2072628#msg2072628