Purchase of ticket at Park

We will be traveling in France in about a month and hope to be able to take the RER to Disneyland for a day. I am assuming that it is possible to buy a one day ticket at the entrance. Am I correct on that or must tickets be purchased in advance?

 

You can buy tickets at the gate, lines are usually short as most people buy them online or have a package deal and get their tickets at the hotel.

However I do think it is better to buy them online, even though the lines are short, they move slowly. When I stand in line to drop off my luggage which is next to one of the ticket offices I am always amazed by how slow the line to buy tickets moves.

 

Most of the time it's also cheaper to buy your ticket on line (more then one day in advanced!) The price at the entrance is always the highest price, no matter when you're there. If you buy on line, you can chose to buy a cheaper ticket if you're not going during the busiest time (which is recommended anyway, if you're only there for one day). There are also sometimes deals on the tickets on line. Note that you don't have to pick the exact date when you buy your ticket, but do consider the price calendar when you buy.