Turns out that these are sometimes called brocantes (which I thought was more antiques places) or marche au puces, but then 'puces' seems to translate as 'chips'. There is a British saying 'cheap as chips', but whatever. I went there one day, past the port and the WWI memorial, around the corner of the Bay and into the Cours Salaya near the old town (Vieille Ville)...and it's called the Flower Market, much more agreeable than fleas.
It was such a busy place I didn't hang about very long; I don't cope that well with crowds. Not all the dealers allowed photos. I'm not sure what they could do about it, but I respected their wishes. There were many beautiful things to see but I didn't buy a thing. It was too overwhelming and I didn't have a plan.
It would seem that I have largely lost the capacity for impulse purchases. I generally need to know what I'm specifically looking for and how I will use it or to recognise that something has been on my wishlist for quite a while. At some time in my past it would have been easy to splash out on buttons, glass gew-gaws, linens, clothes, etc., but for now this sort of spending is more stressful than fun for me. Even when I know I need or want a particular thing, I hold back until I'm certain it is a price I'm prepared to pay: either I know it's a good price or I'm resigned that to have it, I must pay that amount.
Though I'm not as carefree in one way, I have slowed the parade of things coming into my house and have fewer regrets about wasted money. I might be 'mean' about throwing my money at something but then it has allowed me to be carefree in not worrying about how I will meet my living expenses; and we do travel a bit.
Nice is not an inexpensive place. That whole area along the Mediterranean is the one of the world's playgrounds of the uber-rich. The Nicoise dealers know the value of the tourist trade. If there is a place for ordinary residents of Nice to get good deals, I didn't find it.
Also, someone might tell that man who snapped my head off when I aimed my camera at his goods that it doesn't do to 'wake up' the marks too rudely. After all, once the dreamy fascination wears off, it's only just a bunch of stuff.