The are 3 different ways across 3 unique modes of transportation to help you travel from Aachen to Liège. If you're only considering the price, you should check out the train out of Aachen towards Liège, as it is the cheapest to Liège. It's common to find tickets for as low as $11. SNCB operates from Aachen to Liège, so you book your trip with them! Take the train, it is cheaper and more comfortable than the bus!
SNCB offers limited service between Liège and Aachen.We recommend booking the trip to Liège about one week in advance. Though you might be able to find and book a ticket from Aachen the day of, it is best to do this earlier as to be sure you have a seat to Liège. There is usually no need to book these sort of trips from Aachen to Liège in advance. Rideshares should be available on demand all hours of the day.
While buses have recently gotten bad coverage because of cleanliness of bus stations or winter time accidents, they are can be very convenient for travel. The best part about traveling by bus to Liège is that it can be very cheap. That's because they usually have basic accomodations - WiFi and a restroom. Some of the Aachen/Liège buses' coverage has been overstated. The real thing to consider when taking a bus from Aachen is to consider the time of travel and the density of the cities that you're traveling to. If you are traveling by bus between Aachen North Rhine-Westphalia and Liège during high traffic times, you can expect to have your trip altered significantly due to traffic. Further, if you are traveling during winter, the bus schedule might be thrown off due to inclimate winter weather. Be sure to plan accordingly!
The plus side of taking the train from Aachen to Liège? The accomodations, scenery, and lack of Liège traffic can usually be on point. Moreover, you can usually expect your average concessions - such as food and drinks. Most trains have WiFi these days as well. The worst part about trains are the price. While the train to Liège is often cheaper than flying, they are generally more expensive than buses. Train prices are usually set and do not vary as much as bus prices or flights or so the likelihood of finding discounts is pretty rare.