True latex, or rubber pants are becoming more and more difficult to find, ones worth their price. There use to be a number of good producers out there, that would have been worth their price time.
Keep in mind too, rubber pants, even good ones have inherent problems, and require extra care.
That aside, ones I can say are a good choice, are from https://www.inkoswiss.com
They are not cheap, but they are very good quality. They also have a good variety.
You may have some others in mind, I don’t know? But, here is another site that sells rubber items, including adult baby pants. https://www.rubberevashop.com/rubber-clothing/adult-baby-rubber-clothing?srsltid=AfmBOor_WzBpJajAmQDChEw_yFTF8_SsTYXufQxR2DIA8dmCLrrDL9dT
I’m not sure or there quality, but I know of the site, and you can check in there if you like.
There are also some sellers on Etsy, who do rubber pants, but maybe not such great quality. Try searching for “latex adult baby pants”, or knickers.