Casa Castalia
Student apartment. Their price is quite cheap but very difficult to get the apartment since lots of students apply for it.
die Oase Jugendherberge Lugano ostelli svizzera
A youth hotel, the price is reasonable.
From my experience, it is very hard to find an apartment. Especially in the beginning of a new term, lots of students need an apartment。 There are also have language problem. Most of local people here donot speak in English although they speach Italian, French, German...
Anyway, it is better for you arrive here firstly, then get some information from local newspapers and the university.