In case you don't feel it necessary to read yourself, because in this case I have done so obviously, I will tell you here because this interested me also and I would like to share the information.
Someone over in Germany returned a bricked Wii to Nintendo of Europe for repair and NoE charged the dude some €210. The people at hackmii report that there is nothing quite known to be any more expensive than getting a replaced disc drive, a cost of about €90. A new Wii in Europe is, as no surprise, €250. They also conclude within themselves that the only way Nintendo would know it was hacked is if they knew what a flashing LED does when trying to boot the Wii while bricked. They purported that if the bootmii installation fails or does not find the SD card in the slot, one of those two or both, I can't remember, then the Wii will flash it's LED red. Other than that the Wii would be blank and they wouldn't have any visual proof of any hacking. Of course if you can see the Wii menu, then just having HBC or anything else blatantly obvious of hacking will show them your Wii is bs to them. The thing is, there is some kind of ridiculous penalty apparently being forced upon people who send these in for repair. Nintendo does not have to repair them, as they would be obvious to being out of warranty being hacked, but they do and charge you an unprecedented fee. In a letter of return from NoE, or something like that, they apparently think they need to stop HBC, which is understandable from NoE, but doing it by charging preposterous fees for repair is not the way to do it, nor does it seem right at all.
Anyways, after that long, blow-hard explanation, I hope I summarized it sufficiently. If you would like to see the topic yourself go
here.