1. incorrect. FACT, freight is more than 13 Euros flat. Plus the exchange rate bumps the freight up to over $16.00
2. The nipples are actually the reasonable part buying via Rose. A little over 5 cents each.
3. He still has to buy nipples somewhere. You left that out of your "Math". Most LBS want at least a dime
4. Even if your $46.00 number was right (it isn't), 46 - 30 is 16, not twelve.

So yeah. OP can Shop at one place, (DansComp) save over $30.00, get same day shipment, speedy stateside delivery, get nipples included, and custom length spokes. Or he can do it your way. Buy unnecessarily robust spokes, waste, $20.00, then have to shop for nipples at another place. He'll spend at least six bucks there, plus another freight charge.

Why are you fabricating false numbers to support an illogical argument?

I weigh 165 lbs. Should I over spend and build my non-tandem bike cruising wheels with tandem hubs because "They build a stronger wheel"? Of course not. A pair of regular hubs will last my lifetime, and longer.