Why cost of integrated circuits are higher when purchase online than to local market. For example SN7404N on Digi-Key costs around $2 but same i got from local market in $0.2
closed as off topic by Keelan, Leon Heller, Brian Carlton, Nick Alexeev♦, Dave Tweed♦ Apr 20 '13 at 23:01
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If your local market is like a flea market you the price can be anything, and so can the quality. Any correlation between the two is just a coincidence.
That particular chip you mention is a dinosaur: a plain (pre-schottky) TTL chip. The amazing thing is that you can still buy them at all. A marginally more recent 74LS04 goes at 0.25 (or 0.75 if you insist on DIP).
The chip one would choose now (when you would need it at all) would be a 74HC04 or 74HCT04. For some reason they are not particularly cheaper at Digikey, but at Mouser a 7$HC04 goes at ~ E 0.14 (@1, down to ~ 0.06 @1k).
you took a bad example
always look wider than just one supplier (use www.findchips.com !)
if you are OK with flea market quality...