We’re leaving in a couple days and while we have some of the itinerary planned, good 'n cheap restaurants are missing. So what are your recommendations or secret affordable gastronomical destinations in Paris, Bruges, Delft, and Amsterdam?
In Paris I’d recommend you to take a stroll through the Quartier latin - (almost) just across the river from the Notre Dame - and choose something you like. There are plenty of moderately priced places, selling everything from cheap and cheerful (and good) kebab sandwiches to complete menus based on the cuisine of one French province or the other. For the best deal, look for places offering “a la carte” lunches for a fixed price.
In Bruges I can’t tell you where to dine, but I can tell you not to eat at one of the places in the central plaza. Overpriced food for tourists, made from frozen precooked stuff. Awful. You’re better off just getting a snack at one of the fast food stands while searching for a place where the locals eat.
A local from Amsterdam told me that “Dutch food is boring” and if I wanted to eat well for not too much money I should check out one of the numerous South American steakhouses. I tried two of them; one was decent and the other good.
Beware though, even if you do find a cheap restaurant you like: the waiters will casually offer you drinks - and a glass of cola can cost 4 Euros. Alcoholic beverages are even worse.
Moving thread from IMHO to Cafe Society.
There is a scene in a restaurant in the movie A Very Long Engagement, a great movie BTW, and they shot in this place because it looks like 1920. I’ve actually eaten there and it is very inexpensive and the food is great.
I can’t remember the name of the place.
The waiters write up your bill on the butcher paper table cloth. (if that rings any bells for people)
I concur. The Quartier Latin is the place where students from half the universities in Paris congregate to have a bite, so there are tons of cheap bars and restaurants there.
If you’re into Japanese food, I also recommend Higuma (32 rue St Anne, Pyramides subway station) - cheap, plentiful and tasty as hell. The downside is, it’s kinda crowded, at least during the year, because many people know about the place by now. Maybe you’ll have better luck at this date, since half the Parisians are out in the country, leaving the capital for tourists to enjoy 
Do avoid eating or having a drink around the primary tourist spots like the Champs Elysées, Champ de Mars, around the Louvres etc… because you’ll get ripped off for sure. Like 10 euros for a half-pint, 8 for a cup of coffee ripped off.
Another place I ate at and was excellent and inexpensive was the Cafe du Marche
I had the most amazing (and simple) mushroom and cheese omlette I have ever eaten in my life in Brugge, but could not find the place again if the world depended on it; I will say that there are many excellent places to eat in Brugge, but many are quite expensive, as the tourist industry is huge there—Do yourself a favor and wander away from the main square (where the huge church tower is) by getting off the beaten track you will find a multitude of neighborhood bars and cafes that serve the locals, with prices much lower (and food as good or better) that in the more tourist-centric areas.
Have a wonderful time!!!
Chartier is the place to go for great and inexpensive food. The chicken is highly recommended, unbelievably tender.
In Amsterdam you should definitely get some rijsttafel, though I can’t recommend a particular restaurant.
Have a nice trip! 
In the Netehrlands definately go for Indonesian cuisine - usually not that expensive and really typically dutch, oddly enough - and in Bruges you have to get mussels, just because you have to…
We loved Le Bistrot du 7eme, 56 Boulevard de la Tour Marbourg in (le duh) the 7th arrondissement. Not sure what your standard for “cheap” is, this will run about $25 a person American per person for dinner without drinks…but so worth it.
In Amsterdam, try the fresh herring sandwiches from carts and storefront vendors. Avoid the ubiquitous automats selling a variety of mysterious deep-fried things; very authentically Dutch but also inevitable.
In Belgium, there is no need to eat anything except fries and beer.