If it’s Thursday, you can head back towards the center to go check out the Musée des Arts et Métiers for free, as every Thursday evening after 6pm it’s open to the public gratis. Otherwise, make your way to the backside of Montmartre, the place where locals hang. Go to Supercoin, where you can get craft, French beer (a serious rarity in this town). It’s happy hour, which means you can get a half pint for only 3€ and get to hang out with the local dive bar/hipster crowd.
You’re verging on dinner time and you have 3.90€ left to spare. This allows you one of a few options:
-Bike to the Marais and go buy falafel, because if you’re cruising the area around Rue des Rosiers and can’t manage to find a pita in your price range, there’s always the crepe window.
-Hit up a store and buy a cheap bottle of wine (you can, in fact, buy wine for 2€ if you look hard enough) plus a baguette, and some cheese, and do like every cool person in town and go eat by Canal Saint Martin.
-Stay put at Supercoin, drink another beer, strike up a conversation with a cool-looking person and pray that they will share a slice of pizza with you when they order one from across the street.