On Wednesdays in Quillan there is an Arts and Crafts market in the main square and on Saturday there is a food market in the car park at the Train station. 
During July and August there is also a Night market in the Place De la Republic square.
Not to be missed is the Sunday Market in Esperaza which is a combined food and arts and craft market Make sure you arrive early for the Esperaza market as it finishs up around lunch time. In fact its a good idea to arrive early for any of the markets.