Amsterdam is pretty expensive, but then again, so is most of europe. Weed most places is between 10 and 15 euros for a bag that's anywhere from 1.2-2.5 grams depending on the quality. For example, 1.8g of afghan hash at blues brothers was 10 euros, while 1.4 (or 1.6 don't remember exactly)g of bubblegum from the grasshopper was 15 euros (best smoke i had). You generally get what you pay for within a given coffeeshop, i.e. if their white widow is 15 euros for 1.5 it's going to be better than some superskunk that's 10 euros for 1.5. Some coffeeshops are more expensive for the same smoke you could find elsewhere cheaper though so stay away from the 'brand names' like the bulldog, grasshopper, grey area etc. if you're on a budget.
I don't know about hotels, but the flying pig hostels are awesome. The downtown one has a great bar with a deck to smoke on, and a stage with all kinds of cushions to chill out on, I highly recommend it.