Trip to Barcelona

[Greg29]

Hi, I am from Canada and I am going to Barcelona for 2 weeks with a friend for the EPT at the end of August. We have one week of free hotel (my friend won a package), but we need to find a place to stay for the other week. What are the best/cheap places to stay in Barcelona ? Also, I would like to know where I can find the cheapest flight from Montreal to Barcelona. Is Expedia the best site for that stuff ? Thank you !