Pricing for 2010 Prius III in Canada

I've just started looking for a 2010 Prius, and had a look at the first one.

It's a 2010 with 125,000km, premium package plus the solar roof*.

It's at a Toyota Dealership. The asking price was $21,000, recently reduced to $20,000.

According to the Canadian Black Book info, a 2010 with this mileage and navigation (it doesn't have nav, but that's the only option the bb system offers) should have been worth $11,600-$14,300 as a tradein. Average asking price should be $21,300.

On the plus side are:
- premium package and solar package
- the car is in 9.5/10 condition
- Carproof is 100% clean
- it drives like a new car
- the dealership says they sold and serviced the car, and have the service records

On the negative side are:
- the mileage
- only the battery warranty has coverage remaining

I would assume this car would be at the high end of the tradein value, and the mileage should balance the condition and options to end up with an average asking price.

I offered $15,000 as a starting point. The salesperson wouldn't even propose that to the sales manager. There was a suggestion that given it was already discounted, there was no way it could be reduced by more than $1500 (to $18,500).

My past experience has been that used cars from new car dealers typically sell for 80-85% of the asking price. That would be about $16,500, which isn't far from my opening offer and enough for the dealership to make some money on it. Since I haven't looked at enough to develop a feel for what this car could sell for, or if the Black Book pricing has any validity, I thought I'd see what you people think it's worth.

This is in western Canada in case that makes a difference and I'd be paying cash with no tradein.

*(Since most participants here are in the US, here's what's included with the Canadian 2010 premium and solar packages: JBL® Audio, In-Dash 6-Disc CD Autochanger, 8-Speakers, Bluetooth Capability, Integrated XM® Satellite Radio, Integrated Garage Door Opener, Auto‑Dimming Rear View Mirror w/Backup Camera, Driver & Front Passenger Footwell Lamp, Front Passenger Door Handle Touch Lock/Unlock Sensor, Power Moonroof w/Solar Panels, Remote Air Conditioning

Thanks!