I don't know about the initial up front cost and what that Euro US $ difference is, but you should also consider who is going to be your source for customer service and what, in US $'s, that is worth to you I would think and factor that cost in to the equation.
In general I think aquarium product arbitrage is an overrated activity, but that is JMO. Just depends on the actual real price differential and what your personal time is worth I guess.
Good luck and please keep us posted as to how your decision works out.