One of the older names on the Cusco trekking street, and one of the few that puts numbers on the page: the classic Inca Trail four days and three nights runs about US$870 per person in a group of six to eight, US$990 for four to five, and US$1,290 each for a private party of two or three.
They also run Manu jungle trips, which is a different proposition entirely — several days east into the Amazon lowlands rather than up onto the passes.
SERNANP-licensed, MINCETUR-registered at Garcilaso 270. Two mobiles are published for bookings; the linked one is Noe's.