Hey man Just thought I would weigh in here as I have done abit of looking into the cars that your'e interested in at one time or another.
ST205
AS many people have said , yes they are very reliable (ussually) but also genuine toyota parts are not cheap. Also they are getting harder to find with lower kms. People are asking alot of them even with almost 200kms on the clock.
They are not as quick as an Sti (stock standard) and they probably wont be as quick around a track either. However they are still a 6 seconds to 100 car with a high 13 second 1/4.
Nissan s14
Fast(ish) in stock form. Fun. Good luck finding one in good factory condition for a reasonable price.
Sti 4-6. Pretty much the same car regardless of which version you get. The type R had the 180 series diff with a stronger gearbox. However even though it is a 4wd it can get pretty sideways in hurry so if you may need to work up to pushing it around corners more so than a gt4.
The one car not on your list that I would seriously consider is a version 7 sti. They are selling for around 11-15k atm with between 80-120kms on them. Being a GD series they have the following improvments over the GC v 1-6 shape
Much nicer interior
Near bullet proof 6 speed transmission
Much more reliable engine (In consumer tests since subaru released the GD series of cars their reliability has been rated above that of toyota by several independant UK and US tests)
They are between 2-8 years newer than all of the other cars you have listed there.
They have fantastic after market support.
NZ EFI STM and Torque performance all offer a service where for between 1200-2000$ they will reflash the ecus in your v 7 and up sti bringing power from around 165-170kw atw to around 200kw atw or 220 with an exhaust and intake modification.
I mean if you think about it that way you could spend 12k, get a car thats only 8-10 years old rather than 15 and then if you were so inclined spend another 2-3k modding it and have a high 11second 1/4mile car with great reliability, handling and performance.
The only downside to them is some people dont like the front head lights but really that is a small price to pay for a car that will line up with any other car around the same money and have great everyday driveability as well.
Here are a couple examples I found that you may be interested in.
http://www.clubsub.org.nz/forum/index.p ... 048.0.html
if you want a version 6 this is a great car
http://www.trademe.co.nz/Browse/Listing ... =268896563
http://www.trademe.co.nz/Trade-Me-Motor ... 573891.htm
http://www.trademe.co.nz/Trade-Me-Motor ... 750749.htm
http://www.trademe.co.nz/Trade-Me-Motor ... 320440.htm
http://www.trademe.co.nz/Trade-Me-Motor ... 902306.htm
(That one above is even through a yard which means they will probably go lower and throw in a warrenty)
http://www.trademe.co.nz/Trade-Me-Motor ... 110969.htm
EX:89 RS and GT Legacys, 90 EF9 Civic, 95 Integra R, 95 AE101, 90 ST185, 88 Accord, 87 3rdoor and 5door Swift hatch, 91 Pontiac Lemans, 80 Liftback Celica, 95 Hornet 250
Current: 90 3sfe Corona