Computers in germany are usually cheaper than in France, but you have to take shipping into account, sometimes it's cheaper in germany, sometimes it's cheaper to buy in france. It depends on which products you buy.
like cirk said, i've heard some good feedback from
www.alternate.de but i have never bought anything there.
If you have to buy a computer in france, the cheapest way is to buy the computer in Paris in the "chineese" street called "rue Montgallet"
Rue Montgallet is a small street in Paris where there are about 50 computer shops right next to each other, and they keep prices very very very low. They essentially sell individual parts but some of them also make custom PCs, it's the computer enthusiast dream. And if you want a brand pc (HP, Apple, etc..) there's a big brand computer shop called "surcouf" right around the corner, and they also sell individual parts but their prices are slightly higher.
there's a website that compares prices between shops, but the website doesn't lists special packages (motherboard + cpu + ram, etc...) and sinces prices change every day, prices aren't always up to date, so use it just to get an idea of about how much you want to spend and in the end, you'll probably pay a little less but you never know which product have a special offer.
this website is
www.rue-montgallet.com
If you can't afford going to Paris, then there are french based internet shops. The best is to compare prices using a french price comparison website like
www.rue-hardware.com (it's the same website as the one which compares prices in rue Montgallet but this time it compares internet shops only)
There are lots of internet shops and not all have a good reuptation :
here is very short list of very good french sites you can trust : (i've bought many items from them)
-
www.LDLC.com
-
www.materiel.net
-
www.pixmania.com
There are more but those are the only three where i've bought stuff.
you can check the reputation of any shop at the
www.rue-hardware.com site.
The big surcouf shop also has it's own internet shop :
www.surcouf.com