Nickname said:
-the 20 gauge is good if you find yourself in a bind, but you have to remember it is LOUD; and the sound will likely draw more zombies to you.
you should use these as initial weapons only until you can replace them with something better. A machete would be a good hand combat weapon, or perhaps an axe. For range, realistically a bow and arrow or silences sniper rifle would be best, but chances of finding such are slim, so better to just keep the 20 gauge until you happen upon a quieter solution, whatever that may be, unless you do manage to get on a boat or someplace else where firing a weapon would not draw zombie attention.
On that note, shotgun silencers are around $900. If you’re really interested in preparing, that would be the way to go. The don’t entirely silence it but it’s quiet enough that you don’t need hearing protection when firing indoors which should be silent enough to use outdoors with confidence in a zombie killing spree.
Supressors for other guns typically run $500-1200, depending on the caliber and amount of suppression.