there are no hostels in ibiza dood...... well, i think there;s one in talamanca but i dont know how cheap it is.... its right on the waterfront & pretty wicked,..... but NOTHING is really cheap in ibiza.....???
other than that i'd suggest es vive 4a party hotel thats reasonably priced....
they've got their own little niteclub downstairs too...!
Wouldnt say Es Vive is reasonably priced, but its a good party hotel agreed!
Cheaper options young "party" accomodation
JET apts Playa Den Bossa (very young party/close to Space Bora Bora)
IBIZA ROCKS San Antonio (very British, live bands etc)
HOSTAL FLORENCIO San Antonio (super cheap, basic, close to Sunset Bars)
APTS PLAYA SOL, Figuretas (close to Es Vive, much cheaper)
If you want something with clientele average age a bit older:
APTS MITJORN Playa Den Bossa
APTS SAL ROSSA Playa Den Bossa
HOTEL GRAN SOL, San Antonio (Good location for Sunset bars)
http://www.ibiza-spotlight.com/hotel-guide/clubbing_hotels_i.htm