I wouldnt worry about the odd one slipping the net either, there are always bargains to be had and that goes for any car, you never know a sellers circumstance when it comes to how quickly they want/need the money.
I havent seen much change in prices across the board since buying my first 350 2.5 years ago, it would seem though there are the odd rogue cheapy around that I never saw when buying mine.
It will be interesting to see what the next few years will bring, will it go like Docwra predicts and follow the normal pattern hitting around the £3k ish mark and bouncing back or, with nothing else filtering down as what else is there thats similiar (jap sports coupe/big displacement engine or turbo engined) and other cult cars going up in value (supra/skyline/s bodies etc) will they hold their value?