P.S. - I've been reading Trip Advisor forums for no particuluar reason, and there seems to be a myth out there that you can't eat on the cheap in Paris without reverting to, like, boring chain food. But, I'll have you know that this ginormous falafel only costs 5.50 Euros. Take that, Trip Advisors!
Mi Va Mi, 23 Rue Des Rosiers, Paris 75004 (yes, right across the street from L'As du Falafel.)