Originally Posted by Tom.K

lisbon is my favorite european city, great food, cheap, warm, been there more than 20 times

try edreams.com, kayak.com (they have option for +-3 days or week so you can choose best price), vueling.com (you fly through barcelona, you could stay for few days there and enjoy some paella and wine) or ryanair.com, I flew with them to germany few times for ridiculous price, 20 euros return ticket