Not sure for your location, but a good rule of thumb should be for you to get as close to or below invoice price (not msrp) for a new Prius. I've seen some post here that say $100-$500 under invoice (that would be my goal) in lot's of different areas of the US.
Regular Prius or Touring? Higher level Tourings are much rarer. If it's a Touring, $500 below is a bit absurd. If it's a regular NW pkg, it's your call. Find the local dealer that has the exact package that you want and deal with him if it's the exact color. I've mentioned here before that ultimately price isn't the objective. Too many focus on it as if it's their stamp of victory. FYI, the real money is in the rate. 1% on a 20k loan is at least $600. How smart are you to beat the salesman by $200-300 on dealer cost only to pay more on the loan rate? Rule of thumb...the guy that quotes you the lowest number over the phone probably has another trick up his sleeve. Bypass him and deal with that gives you honest information. I'm a dealer and we ALL pay the same price.