I 2nd not buying extremely cheap speakers, it's not worth it. You don't have to spend a ton of money to have decent sound in one of these truck, and with how loud these trucks are, it's a waste to go too high end.
I'm mid level:
Sony CDX-F5700 (Had everything I wanted, Aux-In, MP3 CD and 7 band EQ)
JBL 5 1/4" woofers in the door
JBL 1" Aluminum tweeters in the factory speaker mounts
Polk 6x9s in the rear (plan to replace, they were there when I got it)
Jensen Bandpass 10" Sub w/Cheap 250watt amp
The bandpass sounds great in that location in the truck, and sounds amazing with the rear window down.
Future upgrades:
JBL 6x9's (The front and rear speakers in this truck sound completely different and are very hard to EQ)
4 Channel Amp for main speakers (the head unit does not drive them enough)