Kairon all systems sell for a profit for retailers except for those that retailers buy before a price cut is set, that is why sometimes you see retailers sell those pre-price cut systems at the old price instead of the new price.
The difference in what the retailers pay and what MSRP is does not have much to do with Nintendo's profit at all. The system is probably costing Nintendo $220 to make so they probably sell it at $230 to retailers where they turn around and sell it at $249.99 MSRP so everyone makes money on it.
Games on the other hand only give retailers >$5 each, when i worked at Sam Goody we had a way of finding out how much a CD, DVD, Games, or anything else in the store would profit us per sale. CDs we would usually only make $2-5. This is why u see music stores and game stores sell used products, it really is the only real profit making items.