$400 to $450 is a big part of the cost of an excellent training class that would give you way more skills than buying an SKS would. Buying a SKS teaches you how to degrease a gun covered in cosmoline and adjust a front and rear sight like its 1890. A class teaches you how to actually shoot and use a gun better.
Go to any class or match and count the SKSs there - you'll see precisely zero. There's a litany of reasons for that.
If you're actually serious about being prepared for a dangerous situation, spend your money on training and ammo, not milsurps. If you want to collect milsurps, then forget all the "apocalypse" nonsense. Stripper clips suck. Leaf rear sights are holdovers from massed volley fire at indigenous peoples with sharpened sticks and bows and arrows. 7.62x39 is going to slowly become another milsurp, niche cartridge, like 5.45x39 is already. Cheap Russian ammo kept 7.62x39 viable, but that's going away now.
Be honest with yourself - do you want to buy old guns or do you actually want to be better at using guns?