This happens from time to time because:
1. The airline has adjusted their price since the last time we indexed it
Low cost airlines change their ticket prices very frequently and it's not always possible for LCH to stay totally in sync. We index flights continuously and any price change an airline makes to a flight gets picked up the next time we sync with them.
2. The airline may calculate and display the price in a different currency from the one you chose on the LCH website
Although you can view prices on the LCH website in a number of different currencies, some airlines only allow bookings to be made in one or two of these (EUR, GBP and USD being the most common). Depending on what internal exchange rate an airline uses, the converted price you see may vary a little from the price shown by LCH.
3. ‘Hidden’ airline charges
Some airlines levy additional charges such as admin, booking and payment fees which can be dependent on the number of passengers and whether the flight is one-way or return. These charges may or may not be included within their own initial search results or may only appear at the ‘basket/payment’ stage.
4. Children / Infant prices
Some airlines offer discounts for children which may or may not be shown within their own initial search results or may only appear at the ‘basket/payment’ stage. LCH search results are currently based on adult prices (although we will support specifying children in the future).
Infant prices vary from airline to airline. You can find a link to the airline website to check their policy at http://www.lowcosthero.com/airlines/
In all cases, the price you pay when you complete your booking on the airline's website is exactly the same regardless of whether you found your flights via LCH or performed the search directly with the airline.