I see people mention surplus guns and ammunition a lot, but I don't know that I've ever seen it. Where does one get surplus?
https://www.aimsurplus.com/
https://www.classicfirearms.com/
http://www.jgsales.com/
http://www.southernohiogun.com/ <--- I got my 92S from them and paid a little extra for them to hand-pick one in very good condition. The gun I received was probably never even issued and had very little signs of use.
And probably many others...
If you're looking to buy locally, some sporting goods stores should still carry surplus rifles. You'll probably only see surplus handguns in large gun stores though. The problem with ordering online is you don't have an opportunity to inspect the gun before you buy, so there's an element of luck involved. You have to accept that what you order isn't going to be in perfect cosmetic condition. You also generally have to coordinate with a local FFL and pay a transfer fee, since you can't have guns shipped directly to you unless you're buying a C&R (Curio & Relic gun) and have a C&R license. In general the process is pretty painless.