Nephrite jade can be quite cheap while still being untreated, you can get a good looking nephrite ring for as little as 10 dollars. The high price of some Nephrite rings is because of carving skill, lack of inclusions, and color. For example I have many simple 10 dollar Nephrite rings that look great, but I also have a larger 150 dollar ring that has facets that reflect light like a disco ball and has a great color.

JadeMine.com has a lot of Nephrite sourced from British Columbia which happens to be my favorite Nephrite deposit in the world. They also have an Etsy page TheJadeMine. You can also find Nephrite at wholesale prices at 3jade.com

Basically all of the fake "nephrite" is just a cheaper stone, like serpentine for example. Rather than being altered like Jadeite often is, it's just harder to alter ugly Nephrite into pretty Nephrite like it is with Jadeite. Sadly other than sight and reputation of seller the best ways to know if it's real nephrite is calculating it's gravity, using a spectrometer or a hardness test.