Nothing here is cheap except the trains, and what controls the budget is the boat: a day of long ferry hops and separately-ticketed villas costs more than the bed you slept in.
Ostello Bello Lake Como
The one proper hostel on the lake, at Viale Fratelli Rosselli 9 in Como — five minutes' walk from Como San Giovanni station and about 200m from the ferry dock. Dorms and en-suite privates, a free pasta-and-vegetables kitchen, a 24-hour bar and a garden with hammocks.
Work out the ferry maths first
Navigazione Laghi runs the public boats and sells point-to-point tickets that stack up quickly; the short Varenna–Bellagio–Menaggio car ferry is the cheap one, the long runs down to Como are not. Check the current fare sheet on their site before planning a hopping day.
Trenitalia's train-and-boat day pass
Trenitalia sells a discounted daily lake-navigation pass alongside train tickets to Como, Garda and Maggiore, valid on the current offer until 30 September 2026. If you plan more than two boat hops in a day it is worth pricing against singles.
Never rent a car
Milano Centrale to Como San Giovanni is about forty minutes and to Varenna-Esino about an hour, both on ordinary regional fares. The SS340 and SS583 are walled and jammed, Bellagio parking is scarce and expensive, and a car will cost you more in parking than the trains cost in total.
What a day costs
The bed is the fixed cost and the boat is the variable one. Budget from a dorm bed in Como plus a few euro each way on the Milan regional train, then add two or three ferry hops and one villa: Villa Carlotta and Villa del Balbianello both ticket house and garden separately, and two villas in a day is the single fastest way to blow a backpacker budget. Buy lunch at the Como covered market or a Menaggio supermarket rather than on a promenade and you save roughly the price of one villa ticket.