Ok, not to totally derail this thread but I've seen several people say something about going to gunbroker to get the best deal, every time I go there just about everything is full MSRP!
Lowballing is definitely relative (not an incest joke) but I think asking half of an already fair price is pretty low. On the other hand good grief the prices some people think their children are worth! Just because you paid $800 for it six years ago doesn't mean it's worth that now, especially when a quick slickguns search shows you can buy it new for $700.
If I'm cutting someone pretty low from their asking price I try to send a link to show them why I think what I'm offering is a fair price.
Like this one: https://www.kingsfirearmsonline.com/products/handgun-sig-sauer-colma-pd-sig-p226-40-s-w
TONS of P226 out there for $400 range used. Almost all are .40.
If you aren't in a hurry, you can get great deals on GB. You have to log in and define a custom search for what you want, and hit that search several times a day. After a few days, just search "new in the last 24 hours".
The deals are there , but you have to play the game to get them.