im goin this July, u can fly from lima to cuzco, but in my experience, unlike in europe, s.american flights are quite pricey, bus is WAY cheaper but very comfortable if u get one of the big posh ones, seats go all the way back, good sleep, tvs, its cool. Just ur patience might be an issue, 1.5 hours buy plane, 20 hours by bus, but u prefer it, u get to see the landscape. I did a 35 hour bus ride from sao paulo to Buenos Aires, and it was cool, time to reflect, relax. from my research, all of peru can be done comfortably by bus, lots of bus competition, so good prices to be had, the difference of a second class 'semi cama' and 1st class 'cama' is massive in the bus, but little difference in price, so go for the cama option, or one even higher than that coz then u get a fully reclining bed which makes all the difference when u wanna sleep well, especially if ur tall, i was cool coz im tiny and can make myself comfy. dont book things till u get there and never with travel agents or organisations, u have NO idea how cheap south america is, these agencies take the piss and charge u what u think is a good price, when u get to s.america ull realise u were ripped off coz its ALL SO DIRT CHEAP. Have fun!!!