Prices are a lot lower now than it was about 6 months ago. I always use Carsdirect.com as a base price. Edmunds.com works but not as well because they give you an estimate, and most of the time the estimate is above invoice. CarsDirect gives you a direct price.
When I purchased my 2002.5 Protege5, I only had the Sport A/T, just like you wanted. Carsdirect's price was $16,700 because the car mats were not standard until the 2003 model. I got it for $16,500. Everything is excluding taxes of course. So my advice is to shoot for about $500 below invoice for bargaining power.
Let them know you're serious by showing them the check for the down payment. If your down payment is $2000, have that written onto the check, but don't write it out to them or sign it yet. After that, they'll really know you're serious. After that, they'll throw you some prices. "No we can't do that, we won't make any money if we sell below invoice." Just tell them, "I can get it $400 below invoice at another dealer, but I want the one at your dealership. So, I'll buy it today if you're willing to compromise." If they don't bite, just start leaving and see what they'll say. Then if nothing works, slowly creap down to $400 below invoice. Just follow that pattern and you'll get what you want, but never pay more than $200 below invoice. Considering market conditions right now and it's almost the end of the month, you have a lot of power. All I did was stated a price and showed them the cash down payment I had in my pocket. "$16,500 is all I'll pay. If you agree, it's a deal, if not then I'll go somewhere else." They gave me 3 different higher prices but I kept saying, "Sorry, $16,500 or no deal." Of course they finally gave in.
Remember to be nice with your voice tone too because they don't like rude customers, even if they're desperate for your business. You'll get a better deal buy being nice. Also, Don't take the Factory Rebate either because the 0% APR is better, that is if you can get the credit approval or can get a good cosigner like I did. Good Luck.