Princess,
Just wanted to ask you, have you used the board, or chequed THIS or other webpages
for that matter, to do a search on hostels ('hostales')? You'd find there are perfectly centric, neat and friendly ones for €20-30 a night for a single room. That's certainly NOT expensive! unless you compare their price to those in SouthAmerica (try comparing them to other European capitals!
)
In any case, good luck finding nice lodgings!