Kenav, La Forcola is one example, where I stayed, and I mean the price for a single room for one person.

Try this search, which leads to hotelscombined.com :
http://tinyurl.com/ybzvobc

In fact, trying randomly for Dec. 2, I see La Forcola for 44 Euros (page says 38, but it turns out to be 44), and it's not the only 3* hotel, actually located in Venice, that is in that price range. La Forcola is in Cannaregio, in a great area.