Outer Limits 4x4 Board

HI all,
Considering Upgrading my beloved GQ to a GU 4.2td.
I'm trying to do my budget but its hard to come to a realistic value of my current GQ as the money I have spent in the last 2 years is insane. I understand I'll never get even half of my money back, but I'm just looking to get a realistic value before I consider upgrading.
Heres a list of mods I can remember.

1988 Nissan Patrol LWB TB42
220,000 original kays (Third owner)
No rust at all very minimal dents, original paint
full service history up until I bort it (15,000kms ago)
Good condition interior (no rips or burn marks)
TJM dual battery kit (in cab switches)
ARB bull bar
ARB side steps and brush bars
9500lb winch
lightforce 240 blits spotlights
Uniden UHF radio
pioneer cd/mp3
black widow storage draws with fridge slide
Back windows removed and replaced with genuine nissan solid windows
Safari Tuff Clutch (10,000kms ago)
ARB front and rear air lockers (installed 5000kms ago, all driveline oils and bearings replaced)
Tough Dog 4inch lift panards, brake lines ec (installed 5000kms ago)
35inch silverstone extremes (all 5000kms old)

Motor
Garret gt35/40 (custom built by hypergear)
Tuned length steam pipe manifold
500x300 top mount intercooler
petronx ignitor
ice ignition module
ice ignition coil
2x gas research B2 converters
gas research throttle body
3inch exhaust turbo back
3x gas tanks (1x 120ltr at rear, 2x 20ltr either side of tail shaft
GU bonnet scoop
GU 3ltr air box
Dyno tuned at JPC, made 185rwkw.
runs out of gas at 185, needs twin lines from tanks to make over 200.

I'm sure there are things I have missed or forgotten, Nothing has been spared, skimped on or any corners cut.
This car has given me not one drama since I've owned it, and If its not practical to upgrade then I will happily keep.

Come on guys, This GU 4.2td isn't gunna be there for ever.
I've been offered $12,500, is that reasonable or to low
Also has anyone had any experience with getting a rwc with strait gas turbo set-up, How hard?

mate nice rig, i wouldn't take anything under 14 for that, there's a lot of money spent and it looks nice and straight i know that kind of setup costs a fair bit as i've got a rb30 straight gas turbo. plus you have a winch and plenty of extras. i would hang on to it until you get a good price. road worthy shouldn't be to hard as long as gas is certified, turbo setup has a blue plate and there's nothing silly like bov to open air or a screamer pipe, even with a bov to air some of my mates cars have passed just depends where you go,
good luck

Thanks for your reply,
a rough cost calculation not including bits and pieces that you replace along the way is around the 30k mark.
Like I said, I know I'd never get it back but I was thinking that around 15k would be a fair price. Didn't wanna go off half cocked and be expecting to much thats all. I hadn't even washed it before I took them pics and it cleans up awsome. I'm goin to look at an 02 GU 4.2td wagon today, so i guess I'll make my mind up then.
I'm leaning towards keeping it as I have come to terms with the fact that I will always have petrol flowing through my veins and I'm only gunna spend another 30k on a GU wagon if I go that path.

isn't it extremely laggy with that turbo? massive compared to other setups i've been in

cheers

well to be honest yes it is very laggy. Great once you get spooling, but I'm finding it dificult to drive in high range in the bush.
I'm in the process of organising a smaller front housing through hypergear

why would u replace the front housing ur better off running a smaller exhaust housing on ur turbo i run a gt35r on my tb42 with a .82 exhaust housing and i have no worries with lag at all if anything comes on to hard and fast.