Yes, that is a fantastic site for unused vintage stock. It can be difficult to find an oculist who will replace lenses for you, but if you're in England, Daniel Cullen will do them for you using modern techniques (such as anti-reflecting). The service is quite hefty (at least 120 GBP)
It's important you get 1.5" width lenses, not modern size 2" lenses, as the latter look awful on these. The lenses are naturally smaller as pince-nez sit closer to your eyes. They are not meant to be worn at the end of your nose like you see in films involving old cranky librarians.
Avoid modern reproductions as they have not been designed with field testing (ie they should fit onto your bridge theoretically, but they all fall off). It's due to the fact that making and fitting pince-nez today is a lost science, which used to be a bespoke process.
There is a Czech company that does solid gold pince-nez with diamonds stuck into them, if you have a few thousand euros to burn.
There are certain frames you should avoid aesthetically for your face type, but I don't know what yours is.
There are many types and subtypes, more than you would think, such as astigs, C-bridge, fingerpieces, etc.
Fingerpieces usually need to be sized for a proper fit; the others are universal.
I suggest you go for rimless as they look the most elegant and minimalistic (back when eyewear was seen as proof of one's defective nature, and thus to be made as inconspicuous as possible). They also look the least costumey.
You will likely benefit with the use of silicone nose pads, which are found for a few dollars and vastly improve comfort.
You also need to look into the depth of your nose bridge.
Most are gold-filled, these can range from 10-20 GBP; solid 9kt versions typically range from 50-90 GBP on eBay.
Ear hooks are unnecessary as modern lenses are lighter and very shatter-proof.
There used to be a fantastic blog called Pince Nez Renaissance covering the practical realities of pince nez-wearing in today's time, but the man has made the blog private, unfortunately.
There's a lot of other details, feel free to ask.