Tuconsola.com is trustworthy AFAIK.
Futura-Online is so-so, some people had problems with it in the past. My advice is to avoid it.
Dont know anything about techworld (first time I've heard it).
Good luck.
http://www.futura-online.com is one of the most reliable store in Spain. Is the first official store selling wiinja. Cheap Worldwide shipping. 100% recommended