Guest House RWTH Aachen: https://www.rwth-aachen.de/cms/root/die-rwth/kontakt-anreise/raumverwaltung/~bdst/gaestehaeuser/?lidx=1
single room 42,00 €, breakfast 6,00 €
Hotel am Marschiertor: https://www.hotel-marschiertor-aachen.de/cms/
single room 75,00 € incl. breakfast
If you prefer to book your accomodation independently, here are some other options:
IBIS Hotel Aachen Marschiertor
Mercure Hotel Aachen am Dom
Motel One Aachen
By train
Aachen Hbf is connected via regional trains and ICE.
Within Aachen
You can try to use the bus system but we recommend to enjoy the beauty of Aachen by walking to the venue.