Berlin is better when it's cold. You get the Christmas markets in December and the heavy, comforting food like schnitzel and currywurst without the summer crowds. The history is everywhere, from the Wall to the museums, and it feels more real when the sky is grey and the hotel prices are lower.
A solid trip usually runs about $2500 for a week. We can break that down into smaller monthly chunks so you aren't hit with one massive bill before you even pack your bags. It makes the cost feel more like a monthly utility than a huge financial hit.
The 0% rate is a tool, not a gift. If you still have a balance after those 18 months, the standard interest rate will apply to whatever is left. Pay the $138.89 monthly to make sure you are clear before that happens.