I’m a retired American w/British citizenship from MA permanently living in a smallish town (Montignac 3k full time residents) in the Dordogne. I also have UK pension, so currently - hopefully post-Brexit too - do not have to pay for private health insurance, only the ‘top-up’ which is equivalent to US Medigap plans; I do not know what full private health insurance cost is, but would suspect it doesn’t cost nearly as much as in US, even on Medicare.
Personally, I find that things like insurance (house/car/health), and tax (income/property taxes) and TV/phone are 1/3 of what I paid in the US. I purchased and renovated my house, so I don’t have that expense. The regular bills such as utilities etc are within more or less what I paid in US. Once the initial expenses were dealt with (ie moving, initial purchases for house, cost of renovations etc.), my monthly expenses run about Euro 500 a month, and includes the following: TV/phone services (cable tv, internet, cell phone, home phone [it isVoIP & calls even to US are free] included for 55 Euro p/m big saving there!), netflix, spotify, water, electric/gas, health insurance, property taxes (tax d’habititation, tax foncieres), insurance (car, house, juridique), garden service. Food and other discretionary expenses (not travel) are extra and for me probably average around Euro 750 a month.
I know all this is correct (for me!) because I’m an excel spreadsheet geek and track everything! I’d suggest that you’d want to have a minimum $1500 a month to live comfortably, $2000 p/m no squeeze; if you rent, then you’d have to add that in. This isn’t to say you can’t live on less…I don’t tend to be as ‘frugal’ as I could be! As a few have said, don’t underestimate the initial cost…once you’re settled it’s easier to manage costs (speaking at least some french to begin with and testing the water is always a good idea too!). I have recent new American neighbors who asked me and another long time french expat: we’ve heard all about how much you love it here, now tell me what you DON’T like about living here…and honestly, we couldn’t really come up with a thing! (administrative paperwork aside…lol). Hope that helps!