How much is a ticket from Lisbon to Barcelona?

The cheapest price found today is $24.

When is it cheaper to fly?

Cheapest month is October — from $24.

Cheapest today — $24. Below is what booking services offer.

Departure	Airline	Stops	Price
Dec 6	Vueling	direct	$24	View
Oct 23	Vueling	direct	$24	View
Oct 8	Vueling	direct	$24	View
Dec 4	Vueling	direct	$25	View
Nov 25	Vueling	direct	$25	View
Dec 5	Vueling	direct	$25	View
Dec 21	Vueling	direct	$25	View
Dec 3	Vueling	direct	$26	View
Oct 21	Vueling	direct	$26	View
Oct 22	Vueling	direct	$26	View

How much is a ticket from Lisbon to Barcelona?: The cheapest price found today is $24.
When is it cheaper to fly?: Cheapest month is October — from $24.

Links to booking services are affiliate links. The price stays the same for you.