If you do not want to stay with other HC members, or no one is available, here is what other members suggest.
In Lima, I would suggest not to stay in downtown Lima. Try better Miraflores, San Isidro or Barranco.
Some good hostels are:
Hotels in Peru - Miraflores,Cusco,Sacred Valley
Miraflores - Flying Dog Peru (www.flyingdogperu.com)
Miraflores - Incahaus (www.incahaus.com)
Barranco - Backpackers Inn (www.trekinperu.com)
I've had friends in those places and heard only great comments.