$1300 might be a little too low if you're talking about a 2DIN DVD player in the budget. Those aren't cheap, even used...but without that in the mix...
Mach5 MLI-65 midbasses...not the greatest midrange out there, but it'll get you started until you can upgrade to Seas CA18RNX's or Peerless Exclusives or something. Under $30 for the pair, IIRC.
Seas, Vifa, Dayton all make very good affordable tweets, just depends on how much mounting room you have. Let's say $50 for a pair of tweets.
A used 4-channel amp can be found on
Ebay or the forums for $200ish or less. I'd look for stuff like a PG M44 or similar...older, but if the previous owner took care of it it'll blow away newer crap that sells for more.
OK, so that puts us at under $300 for the front stage...minus sound deadening. Add $120 for that, just to start.
Little under $900 for the rest of the system...decent subs like Dayton References, Exodus Audio's drivers or Shiva-X's can be found for $150 each. Suitable amps can be found used for $200, again, vintage or older is going to be your friend here.
The DVD player is going to be what you'll have to work the budget around, while it's easy to build something for under $1300 without one, you'll have to find a hell of a deal if you want everything under $1300. I'd say going to two grand is much more reasonable.