Flights & baggage fees from Paris to Lisbon

Baggage fees are charged by the airline, not the airport. You need to look at the airline website to find out the costs, it varies from airline to airline.
Also, pay for any checked-in bags at the time you book your tickets. If you only pay for the bag when you reach the airport it can be double the price.
Airlines, especially the cut price ones, are adding fees for checked-in bags allegedly so the passengers with only hand luggage are not subsidising those with checked-in bags, but it also helps to keep the advertised headline price low.

Adding to Chris F's excellent reply: in addition to the budget airlines, check TAP and Air France. The base ticket price may be higher, but these are more likely to include one checked bag in that price, so the total price can be the same or less.

To find all options, start with Skyscanner: http://www.skyscanner.com/. Then go to each airline's website to see what their baggage policy is.

I have booked and used several inter europeon airlines and as said.. all price luggage differently ( mind you most I have ever paid is 15 euros per bag.. which airline are you looking at??)
Check out Easyjet, and Vueling too.
Always pre pay for luggage too.. the fees at airport are always higher.

Book directly with airlines.. not through a TA too.. and READ each site carefully for restricitions on carry on,,, luggage and weight.

Thanks all for your replies. Very helpful. We booked with Aigle Azur, has good reviews and they had best flight times for us. I booked directly on website but never saw option to pay for checked bag. Will probably try to call them.

Thanks again.