R34GT4 and with left over put rb26 in it to make a 4door gtr but the year is wrong. sooo most likely a... evo of some sort.

the evo seems to be popular and something I hadnt considered. with the merc i would be worried about servicing/parts. ace I was aware of cuts's car but I havent seen it yet. there are so many other options in two door but I need to have a child seat. so far my list is
 
evo
golf r32
focus xr5
alfa 159 jts

If you are considering VWs then look at a Passat Wagon, either Highline or R36 V6 or the V6 CC if you are looking for performance or the 125 TDI. I have a 2009 Passat CC TDI with a cheap reflash provides 151kw and around 5l/100km long term. 85000km.No warranty claims and service around $350 each 15000kms. Market price now around $30000. I went into buy a Golf R32 and walked out with the CC, Here is a petrol CC example.220 killerwasps and 4WD and a great drive. More space, more style and quicker than an R32. Heaps of rom for a baby capsule or seat.  http://www.carsales.com.au/private/details/Volkswagen-Passat-2009/SSE-AD-2303504/?Cr=4&sdmvc=1
 

Just do this. 
I mean at least the steel in chassis mods is newer than 2006 :P

That's a really good budget. I'd go with one of the below (all within):
 
Evolution 8 GSR with bolts ons (piping, exhaust, 3port boost solenoid) & flash tune
Fastest, best handling, practical with lotsa local knowledge (parts/support). Factory issued with recaros etc & many of the examples for sale have a few goodies (exhaust/coilovers etc). I can also help you as a friend of mine has the flex maps for the 8 ECU (ie you can run 98 to E85 with a flex sensor on a STOCK ecu)
 
Toyota Mark 2 JZX110 (If you want to be an all Toyota man)
1JZ single turbo VVTi, handles really nicely, apparently great on fuel, lotsa room, bulletproof engineering. Look good with a lip/rims & don't stand out as much (from a theft/police perspective).  I know Cuts (ST205 boy) in TAS is complying a Mark X at the moment, but realistically you'll be waiting ages to get one yourself.
 
IS250 (if you want to be more "adult")
Not fast at all, but maximum reliability & comfort. Great on fuel too & with a simply lip/rims, looks very classy indeed.
 
Nissan 370GT - 4door
Same powerplant as the 370Z, very modern/luxurious interior. Nice handling, look good (imo), especially with rims. Looks just like the local pricey enfiniti's. Navigation etc can be converted to AU/English.
 
I've excluded everything European or American due to build quality and/or maintenance requirements. I'll probably buy Japanese cars for life.

a secondhand STI for sure

If it was aussie delivered, split it between STi/Evo/R34. Depending on what you like about the cars.
 
If you were going for Import, definitely check out some of the Toyota's on offer. Even though they might not go as insane as the three above, they are a lot more practical and comfy.
Even if you want to compare to more comfort orientated cars here, eg. XR6T, Aurion or even Subaru Liberty GT, the Toyota's are much cooler and that little bit better build quality.
 
If I had 30k to spend though, I'd save up a little more and buy an 86, or finance one and use the 30k to pay for a Crawford performance short block and turbo conversion ;)

+1 on the Mark II JZX110!! (I'm a RWD man). True modern sleeper
Euro cars are $$$ but The Golfs aren't too bad if you can do some DIY and has DSG...

stuka.....what would you buy?
 
4 doors
decent sized boot
decent power 150kw +
decent handling
relatively modern 2006+

 
For that budget I did own a 2007 Subaru Liberty GT spec.B Wagon and was planning some light mods with the change.  3-4mths later it was in the panel beaters for a minor repair when an arsonist burned the place to the ground (with my car inside).
 
I loved that car and would buy the same again, but probably try and get a 2008 Liberty GT 'tuned by STi' with < 100,000kms.  Alternatively I'd be looking at a VW Passat R36 or V6 Turbo-Diesel Mazda6 (or TD Audi A4 quattro if within budget).
 

KnightrousI would ignore all the requirements outlined in the first post, then buy a Lotus Elise for $20k and spend the remainder fitting a 2GR into it :D

 
While ignoring requirements don't let a small detail such as budget restrict you, substitute the 2GR with an RST V8 - just as much effort to squeeze in with greater reward!  Personally I'd spend the money on a 2003 Lotus Esprit V8 SE (UK import).

Tuned by STi GT's in good nick you don't get much change for 30k.
 
You could however buy my 05 GT for 10k (which already squeezes just over 150kW with a light tune) and spend another 10k doing an EJ207 STi conversion, brembo's etc. And have something faster.
You just don't get all that facelifted goodness.
I love Liberty GT's, but unless I needed another family hauling wagon, I wouldn't get one. They depreciate so damn quickly.