There's already loads of great advice in this thread, but I thought I'd chime in as well...
You can check what people are paying, on average, for new Versas at
http://www.edmunds.com as well. They have their "TMV" (true market value) evaluation, and for the Versa the nationwide average selling price is about $50 to $100 off of sticker price (depending on options). So, like others have said, there's not much room to budge on these, especially since they are low-cost to begin with.
One more piece of advice is to use a loan calculator to estimate your payments on the price you are willing/expecting to pay. You can go to this site to do so:
http://www.finaid.org/calculat...phtml
You put in the loan balance (amount to be financed), interest rate, term (and you can skip the minimum payment parameter) and find out what the monthly payment will be (of course I'm assuming that you will be financing this purchase). Like Martini said, Nissan has some great financing options, so you can use their interest rates to guide your loan calculations.
The reason I say to do this is that when I got to financing, $1500 had magically found it's way back onto my total cost, which I had negotiated out of them (I had a trade in). In short, had I not done payment calculations prior to going in, it wouldn't have instantly registered with me that the monthly payments they quoted me were incorrect.
This was my first new-car purchase experience as well, but I went into it armed with all sorts of advice from friends and family. I was at the dealer for nearly 4 hours, even though I walked in and said, "I'll take it" from the get-go. Negotiating the price took a long time, and by the time I got to financing, I was tired and somewhat rattled from keeping various numbers in my head. They first show you the monthly payment, without quoting the total loan amount, which is tricky of them. It's easy to get overwhelmed by all the info during the purchase, so go armed with as much knowledge as possible...and let them know you're knowledgeable. They tried to take advantage of me because I'm young, and it was clear they weren't expecting me to deal with them like I did.
National Base for SL Hatch with CVT: $15,550
ABS: $250Sport Package: $700Convenience (req. w/ sport package): $700Destination: $625
Total: $17,825 MSRP...TMV: $17,768 ($57 off MSRP)
ABS and Spoiler only: ~$450Destination: $625
MSRP: $16,625
[edit: I went back and read the above replies thoroughly and found that the spoiler can be installed by itself...so you could knock off a few hundred bucks by not getting the whole sport package...which would also mean that you wouldn't be required to get the Convenience package, which would chop off another $700. So assuming they'd put the spoiler on for, say, $200, your MSRP would be around $16,625 or so, like ThirstyRoss said before.]
Modified by Rockhound at 11:32 AM 5/31/2007