mediamarkt is very expensive indeed - same with alternate actually
my brother always ordered at
www.conrad.de and last time i got my stuff at
www.reichelt.de
Conrad offers a lot more than just computer parts, about all kind of electronics you can imagine. Reichelt is sometimes a bit rare because they dont sell every crap if they know it is crap. i think they provide mostly quality items but i dont know if they are 'cheap'