Etap Hotel Alexanderplatz, Mollstrasse 30, gives me a rate of 53€ per night for that weekend. It's a Accor chain so I wouldn't worry about quality. So, I'd go for it if I were you.
http://www.accorhotels.com/fr/hotel-...tz/index.shtml
It's apparently opening this month.
I've booked a room in this hotel. It seems like a good location and a safe choice. I will report back my experience.
berlin is a good city to use priceline. you can get some good deals depending on what's going on in the city.
I've used it once for Montreal and royally screwed it up (my fault) ended up spending nights at the boonies somewhere because I clicked wrong and there was no recourse thereafter.