Inexpensive stores

Reported - off topic.

There are a few stores that come immediately to mind. Large Extra Large in France is usually an American size 12

A Monoprix that carries women's clothing is most like M and S
Camaieu* is a French company
Mango and Zara are Spanish. I mention the origins because their garments are cut for small boned Spanish and French women and no matter my size my Northern European Midwestern swimmer's shoulders couldn't work with their garments.

H and M being Swedish has a more generous cut but not the style of the above 3.

A walk down Rue de Rennes from the Gare Montparnasse will take you past many others

Also Tati, although some people think that the name describes the quality.

Thank you all for this info!
BTW, where are C&A, H&M, and Ulla Popken located, please?

Are you asking about the store locations in Paris? I can’t help you but I think maybe Google can.

I would suggest "Monoprix" where I've bought three shirts, to be exact, in the past. Monoprix definitely has a clothing section, the best chance for a sale is in July.

Well, we are going there October 20.
July sales are in the past!

Use Google maps to locate the recommendations given to you that are near wherever it is you're going.

I used Google maps, works fine!
Thank you.

Reported - off topic.

Reported for what? How can it be off topic when the author was the one asking the original question?

JC, thank you.
Honestly, I do not care he reported me.

I like Caroll. They have several locations in Paris and I've seen them in other cities as well. Their website gives store locations. I'm not sure how the pricing, or their size range, compares to Marks & Spencer (maybe a bit more?) but it's at least more reasonable than a lot of the boutiques you pass by.

Or maybe a fabulous Parisian scarf that can jazz up the clothes she already has -- and drop into the conversation at home.

I have found some really great clothes at the Bastille Marche on Thursdays and Sundays.
This is an outdoor market next to Place Bastille with a lot of food for locals, a lot of touristy tchotchkes (sp?), and some clothing vendors with a range of styles and sizes.
I have bought several lovely Italian linen pieces from the woman located very close to the Bastille roundabout. I'm an American XL.
It's also got a vendor with the best prices on cotton striped French long sleeved tees.
She can also wander through the Marais for some fun boutiques.

C and A has the best prices, IMHO.
They have a branch on Rue de Rivoli in Paris.

I also don't understand why anyone would report this OP's question??

Ask Paul-of-the Frozen, please.

I don't think the OP should have received the "off topic" response, but also think he could have added a little more information in the post -- like mention he was looking for inexpensive stores in Paris, with XL clothing.
C&A on rue du Rivoli has larger sizes and is not expensive. I like COS on rue des Rosiers in the Marais. I am an XL and always find nice things there. Reasonably priced and quite stylish.

Many of the outdoor marches sell clothing at very reasonable prices.

Maybe it was reported as off topic because there is no statement as to where in France the OP will be. It seems that responses are assuming Paris. But is it Paris, Dijon, Lyon, for example or all of France. I love Caroll but it is not inexpensive and their size range is too small for the typical American XL, but then again, I have no idea where the OP’s wife is from. There are number of shops with a range of larger sizes near Galeries Lafayette but if she is an L/XL, she could be too small for Ulla Popken and does not need to shop in a plus size store. I am a women’s XL and find clothes in Paris in many stores but never at Monoprix or Caroll. There are a bunch of inexpensive shops on Rue Saint Antoine west of Bastille — I don’t know the names but they are on the left side as you head west from Bastille right around where Rue de Rivoli begins. There are shops in the low numbers on Rue Saint Placide and there is always Uniqlo, Tati, and Topshop.

OP wife is from US, she will shop in Paris, France.
Sorry for omitting these details.