You need to look for basic GPS not SatNav.
My phone, a Nokia 5230 has built in GPS, it does have SatNav for driving but it also has a basic map function where it just pinpoints where you are on a map.
Maybe try the walking or hiking sites for something.
is it def an FZ? or FZR steel as opposed to alloy framed.
£1k is at the top end of the FZ range, it would have to be MOT'd and running sweet for that.
I would offer him £500 and get to £800 if your confdent in cleaning carbs. That's if the bike hasn't been running for a while.
there's an article in December's Practicle sports bike on the FZ and they promote an 80's race foemulae which the top 10 bikes are FZ's
It depends how much it's worth to you. A £1k seems a lot for a bike without tax and test,but I haven't seen the condition. If you want it and have the cash, get it. Seems a bit over priced to me for an 89 model. I'm sure you can negotiate a better price.