no, i'm not an AROCA member. not much about AROCA appeals to me unfortunately. if there were regular show'n'shines, maybe, but the track days and infrequent social events are not for me.
KONI Sports were ordered through my local KONI supplier (in geelong). around $1100 a set from memory. i also had them on my 156 TS, and remain one of the best upgrades i've had (also had them on an '95 MR2). the adjustability is a great feature. and cos of this - plus being considerably cheaper - they were my choice ahead of KONI FSD's.
i had them fitted by Lance Dixon Alfa, where i've bought and serviced my alfa's with. fitment would have taken the total cost to around $2K, but i had them fitted as part of my new-car purchase deal; that is, when i bought the GT, i had them throw in the labour for fitment of my Eibach springs and KONI's.
the ride quality and handling are greatly improved over the factory alfa dampers, especially if yours have had a lot of k's under them (eg: 80+ thou).
i suppose you'd want to confirm you can find the front springs alone to suit your car, if you buy the rears. obviously, there'd be no point if you ended up having to buy a complete set of fronts/rears just to acquire the fronts.