Hi, cimet--
Do you mean "youth hostels" or "hostales"? These terms mean different things in Spain, though they sound very similar. I am guessing from your budget that you're traveling as a student...in which case you might be interested in youth hostels--the typical backpacker, dorm-style places. Those go by the name "albergue juveniles" in Spain. You can search the bulletin board for those and also for inexpensive hostales (which are small, usually family-run hotels--individual rooms, some with private bathrooms, some with shared bathrooms). There may not be as much of a difference in price as you might expect--the bigger difference will be in whether you share a room and bath. Either way, have fun!!