I mean a site where people can buy for an example parts for ur pc and not only that but monitors,mouses,bluetooth,motherboards, processors and such(and alot more)
So how much will it cost realizing this and how can it be done, what do i have to do?
You can make one, or go to
http://opensourcecms.com/ and try out the ones in ecommerce. If you like it you can get it. Most of them are free.
No i mean make it
Not the site but how do i work with stores that would provide the stuff and how will i profit from it
You will have to buy there product and sell it your self. If you want the best deal you have to contact the manufacturer or one of their distributors.
You can't just majically click a button and get the stuff for the shop.
You would also be advised to take advantage of Economies of Scale. Good luck, and... goodbye.