There's also quality to consider.

Wally World and Big 5 sell mainly "Entry Level" or off-brand shotties for only a few cents less than what you would buy anywhere else. Their higher-end stuff isn't any cheaper and sometimes even more expensive.

If you want used, browse the classifieds; If you prefer new, start prowling the Gunshops and the 'net.
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The art of government is to make two-thirds of a nation pay all it possibly can pay for the benefit of the other third.--Voltaire