Take the RER (A line) from MLV/Chessy at the parks and get off at Etoile/Arc de Triomphe. Takes 45 minutes. Walking down the Champs Elysees toward Place de la Concorde, Laduree is on the right hand side number 75, about a third of the way down. You cant miss it - the facade is very distinctive.
Last year the menu prices were per item, ie no set menu and were quite expensive. However, I remember the macarons (note NOT macaroons) were about E1.75 each or E27 for a box of fifteen. Well worth it, fabulous creations .. We had tea and sandwiches for two, with the macarons and it came to around 60 euros IIRC.