There is a restaurant chain in France called Flunch where, for a really low price, you can have a good lunch/dinner.
The menu du jour or menu express, just 6,20 €! (Oct. '09). A main course plus drink and all the salad, rice, pasta, chips, etc. you want/can eat.
I'll give you the address and phone number of the one I visited; I really don't know if there are more in Toulouse.