Zmann is pretty spot on, tough to make a complete package around $1k but it is possible.
Going to be a non nav not crazy fancy HU, but good enough.
SPL2k will get you a killer setup, or build your own box and stuff it with a Pioneer or Rockford Fosgate (after some research posted in another thread, I would go with the RF sub, but haven't listened to either) shallow sub.
Maybe go with these up front $99,
http://www.sonicelectronix.com/item_12224_Pioneer-TS-D1720C.html
I personally would skip on rear speakers for sound and budget reasons but if you want, throw in a decent pair of 6x8 coaxials, probably another $100.
and I would throw in an amp like this,
http://www.sonicelectronix.com/item_67930_Hifonics-BRX640.4.html
Setup the amp in 3-channel mode to power the front speakers and then the subwoofer, and if you do rear speakers just run them off the head unit power.
Going to need another $50-75 roughly for wiring and miscellaneous installation, but should have a decent complete system.