you get a 003 error most likely because your wii is a korean modded wii and you went online with it to perform a firmware upgrade

how much to fix this?

if you are a modder yourself (and must be quite a good one)...i believe it will cost you not much except some tools that you may not have with you(i.e screwdrivers)

but since you asked...well, it will depend on your own local gamestore to fix it for you...(i don't exactly know the price...sorry, some would say that you need a modchip or whatever...they could be lying...or maybe it's just a different way to unbrick your wii)

hope that helps