Yep, it's a Izhmash Saiga Model 410 - no matter what the importer etched into it.
Manufacturer is Izhmash. Izhmash factory is in Izhevsk (geograpically). Doesn't matter who imported it (Arsenal, FIME, Legion...) it was still made by Izhmash in Izhevsk.
There is no such thing as a Model Saiga 40. They are all stamped SAIGA 410 somewhere (depending on the manufacture/ship date) - before they stopped being imported in 2014.
pix603705419.jpg
Legion (Legion-USA, prior to 2014) is/was a branch of Izhmash. (Like Dan Wesson Firearms is part of CZ-USA) Legion is like the custom shop for Izhmash manufactured firearms.
So...
Still stand by a $400-500 book price. Everything else is subjective. You may be able to get another $250-$300 for it from a "really have to have one" excited buyer.
and...
add extra $ for each "Legion" accessory/item. Legion SAIGA 410's ship with no muzzle device, one 4rd mag and all other original ruskie parts - unless upgraded (hint: a TAPCO G2 trigger doesn't come from Russia).
link to Izhmash Legion site
This is how they come to the importer. (click pic for larger version or visit link)
2162a425-b435-4cdc-8508-ffc2b80334c0.jpg
I don't think your guy knows what he's talking about if he can't explain that to you.