I know I'm replying to an old post, but I'll do it anyway since it may help someone else.
Mine makes the same noise, but almost always when it is below freezing outside. It seems to be normal and is caused by the shrinking of some of the materials used in the blower fan which is causing it to rub.
While I haven't replaced one in an ILX, I've done them in a few other models of cars and it isn't extremely difficult since they are usually right behind the glovebox.
Im fairly new to this platform but thought id chime in. Recently had my blow motor replaced by a local shop it was fairly easy from what they said and cost of both the part and labour were reasonable
$80 for an oem unit and $50 for labour I believe.