Cruz del Sur run daily buses to Lima at 11:30AM and at 2:30PM. The trip takes 7 hr approximately.Arequipa is 8 hrs away by bus. Cruz del Sur offer buses at 3:00PM and also later in the evening. Most of the other companies' buses leave in the evening from 10PM-12 midnight.
Ica is 2.5-3 hrs away, various companies run buses throughout the day. Prices start from 7 soles.
The long trip to Cusco from Nazca can be broken up into three legs if you don´t mind being called "gringo" when hanging out in the intermidiary towns. Hourly colectivos ply the paved, but curvacious, road to Puquio where you will find 3 simple hostals near the main plaza 18 soles a night for doubles with bano privado. From there, buses head another 6 hr 40 soles to Abancay. In Abancay, you will find that the Hotel Paraiso next to the bus terminal is your best bet. From there, Cusco is a 5 hr bus 20 soles ride on an equally winding, but paved, road.