Good eats, easy on the wallet, in the Montparnasse or St. Germaine des Pres areas?

We need to know what you consider "inexpensive" and if you are thinking of lunch or dinner. Most neighbourhoods have at least one Italian or Thai restaurants, by the way, and all restaurants are obliged to post their menus on window or door so there can be no ugly surprises.

I am looking for lunch or late afternoon options (4ish) for about 5-10euro per person.

Thanks.

Monoprix for take-out sandwiches, fruit and yogurt ?? Take it to the park.

Pepita, we have not eaten here yet but I've had it on my list- Cosi is at 54 rue de Seine. It gets good reviews, looks like with some discipline you can easily be in an 8-12 euro range. You can see it on Yelp, and also search per arrondissement and price range.

Cosi is great with a diverse assortment of sandwiches and salads. Often a line, menu posted on wall near cashier and you eat upstairs with a few tables downstairs. We love it and since we often stay in the 6th or 7th, it is perfect for a quick lunch.

Pepita,
I think 5-10 euro is a bit too low for a good lunch in Paris restaurants. You might be able to squeeze by shopping at the Monoprix.
In the Montparnasse area, I suggest Creperie Josselin, 67 rue du Montparnasse. Large servings for around 15 euro. Maybe the kids could split one. Along this street, there are also Chinese and Japanese restaurants.

If you head south on rue du Montparnasse, it becomes rue de la Gaita. If I remember correctly, at the intersection where the streets change names, there is a fairly inexpensive chain gelato shop where your family might enjoy dessert.
If you go to rue Raymond Losserand, you are pretty much in a local neighborhood. The restaurants were way less expensive that in the more touristy areas. On average, a set menu lunch was around 12.50 euro last summer. At #65 is the 2013 best baguette.
At 82 Boulevard Montparnasse is EXKI. It's a chain but offers healthy salads, soups and sandwiches. There is a website if you want to see the menu and prices. The food was really good. You can do takeout which is less expensive than eating there. Walk over to Luxembourg garden to picnic.

Following. :)

If you can get to Au Bon Marche, the food store part of it, they have a great deli section where you can get almost anything you want....salads, sandwiches, meals to heat up.

If all else fails, find a boulangerie and buy a baguette and cheese and a small bottle of wine. Nothing beats that!

Thank you for all of the helpful leads. I will try them. If I find any on my own, I will post about them for others.

We ended up with a good routine ... French for brunch and Asian or rotisserie chicken with potatoes for dinner. There's a good market where Rennes & Raspail intersect - we bought lots of roti chicken there (6 euro per chicken), fruits, and vegs. There's a good rice & noodle shop on Rue Littre - reasonably priced soups and nem and super nice service. We found three bakeries that we loved for morning quiche, baguette, pain au chocolate. Yogurt and milk from the grocery store. This kept our daily meals to about 10-12 euro per person.

Pepita-good to hear, and thanks for reporting back. Sounds like you mixed it up well and worked it out, a great experience for the kids. Welcome home!

Thanks, Dave! We are still on the road but I am grateful for the "welcome home!"