First off, if you don't know, the 240SX is dead and collecting rust in my driveway. After going over my finances, my father and I decided my best course of action would be to finance a car from a used-car dealership. My friend recommended a dealership that does a minimum $2250 push-pull-tow trade-in for used cars. He said they may pay more: A girl he works with traded in a beater Subaru with a door stuck closed and they gave her $3500 for it. He traded his Dodge Ram and got the $10000 he needed to pay off his balance on that, then got a good interest rate on a Jeep Cherokee.
They have a WRX wagon, Mazda3 hatch and an RSX that I really like (as well as [yuck] Neons and Crapaliers if I can't swing for something nice). What kind of advice would you guys give for a first-time financier like me?  

Well, do some research about the company and so on.  As much as you can.  Afterwards, go out and get the mazda3 and enjoy.  

I'd take the WRX wagon and be done with it. You still get the pedigree of the WRX with AWD and turbocharged goodness, but you add a little versatility to boot.  

I'd swing more twards the RSX or Mazda3, but that's just what I'd do, try and get the best deal, if they won't take what your asking for and it's modest,seeing as that's the only price you can really afford, do something like walking away and saying something like "well, sorry I can't take your offer, I'll probably go to that dealership(rival dealership) that had that real nice, real cheap (car that your gonna buy) with the sport package" or something along those lines.. works everytime. Id be great to get 2250 on that 240.. especially in the state it's in..  

i'm lovin' the mazda3 idea, and good find on the 2250 or more deal.  

2GNTEclipse:
I'd take the WRX wagon and be done with it. You still get the pedigree of the WRX with AWD and turbocharged goodness, but you add a little versatility to boot.

I like the idea of the WRX wagon the most, but it's more expensive than the RSX and Mazda3. The main determenants of what I can get are the monthly payments and the insurance costs- that's why I also have to have the Cavalier/Neon/Elantra/etc. on my list. I haven't had a chance to make a budget, but I will this week. No doubt the WRX will have high insurance payments, but a friend of mine from NH said that since Mass. regulates insurance rates, it's actually cheaper to insure certain cars in MA than NH (He found this out when looking into one of the new GTOs). That particular friend also has hook-ups within the dealership I'm looking at (They gave him enough for his 2003 Ram to pay off the remainder of that loan and got him an excellent loan on a 2004 Grand Cherokee), so I'm going to leverage that the best I can.  

Buying any car and basing what you can get off your projected monthly payment is a bad idea. Trust me here- I'm having the same idea with regard to my car despite nothing being wrong with it. I want a new GTO SOOOOO bad, but I keep telling myself no because I can't afford the offset between insurance and increased fuel costs; not to mention, the increase in the cost of the car itself would probably do me in. Bear in mind that I'm 32, have a good job, and a clean MVR.

The shorter the term of your finance, the less you'll pay for the car in general. This will also reduce your getting "upside down" in the car and actually owing more than it's worth.