2 Places come to mind, PC club, east on sahara, Computer surplus outlet on Patrick Lane, about 1 mile east of the airport.
I bought cat 5 cables there, 10 footer's for 3 bucks and 50 foot were around 8 bucks.
Computer surplus outlet is a dream place for Geeks, tons and tons of stuff, they have some earphones for a buck and new mice for 2 bucks right now.
There a lots of good places in Vegas to buy stuff.
Bleep