As mentioned before, im looking to buy a SSEI so im just trying to broaden my knowledge..
So if i need to buy a used sc from a private seller or a junk yard what should i look for to know it has alot of life left in it?
Im guessing check for play in the snout, but also moves freely. leaking snout oil, there is a coating on the impellers correct? so make sure it isnt coming off? make sure the threads in the mounting holes isnt striped, dings on the rotor "blades"
anything i am missing?

Bump......

First, look at the rotor coating. If it'* wearing off that'* a good sign the needle bearings are going out. $50+ Check for coupler play, check for end play in the snout shaft. Count on over $100 in parts, plus you need someone to change them.

What should i expect to pay for a used SC in good working condition?

At a junk yard, expect to pay around $150. That'* to much. I see them on craigslist for $100-$125. Some people set the price way to high. In my opinion, if your paying over $125 your paying to much. If your looking for a gen3, I have 2 of them here and want $125 shipped.

any mods to use a Gen III?

A gen3 is the standard M90 that comes on the L67 from 96 on

o i c..