For me. Probably my latest birthday present from one of the guys on here. 1:48 F-4E Phantom 30th anniversary. Or possibly my Dragon 1:32 P-51D-5-NA at $75NZD

Italeri's PT & MGB's

My most expensive in the CH Tiger I with Wittmann markings at £75. Second was my current build, the CH Panther with Pz IV turret at £70.

The one that will take up the most space is my 72nd B-52D. Though i think the 32nd Ju 88 will run it close.

I have the Tamiya Yamato, the new kit. its probably the biggest and most expensive (as I have all the photo etch). To be honest its going to sit in the stash for a while as it scares me a bit

A close second would be the Zoukei-Maura A-1J Skyraider for size or the Airfix Mosquito. 

Phil

eduard 1/48 su-27 special edition (plus all the AM i could find) The AM probably cost as much as the kit 

My biggest kit is a Tamiya 1/350 New Jersey, which should also be the most expensive, but it was a gift which makes it one of the cheapest.

My most expensive kit would probably be the Eduard 1/48 Fw 190A-5 Profipack, which I made the silly mistake of buying locally instead of getting it from overseas.

Trumpeter 1/72 TU160 Blackjack bomber. BIG mother f-er. I also have the Backfire bomber to go with it. Still have my eye out for the Bear....

1/350 Hasegawa Akagi    biggest and most expensive

I've had it in the stash for a few years,and I won't build it until I retire and make my final move.No way do I want to spend months on it,then wreck it in a out of state move.

Well, I'm not sure of the most expensive, but the biggest must be my Gene Hooker 1/72 vac C-133 Cargomaster!  It's going to be a beast someday... :)

-Derek

My biggest and most expensive is the Trumpeter 1/32 F-14A.  Bought it for myself for my birthday this year. A bit intimidating to look at.  Will wait until i get more experience (and shelf space) before building.

Bronto - that 1/35 Dora is a monster! Hope you post some pics when it's built.

Largest kit and most expensive kit "at the time of purchase" is the Minicraft/Hasegawa P-2 Neptune I have to convert into the AP-2H. At the time I bought it, it cost 6 Hasegawa Phantoms (first tooling). After years and years, I have the conversion, Zotz released decals, and I have the parts for the flares I want to load it with.

Most expensive recent kit is the new tool Hasegawa F-4G Wild Weasel,,,,,,I found one of the "Blue Box" kits at a show, and was okay with paying the collector's price for it,,,,,,,just months before the kit got released for only the second production run in that molds' history (the old decals didn't come in the new release, though)

Wow, no one here does garage kits???

Most expensive is a Star League Gunstar from the mid '80s movie 'The Last Starfighter'. Giant hunk of resin about 1/48th scale I think, cost me something north of a hundred.

Plus a bunch of other SF kits, from Babylon 5 and other series - all limited run and insanely expensive...

My most expensive kit in my stash is the 1/48 scale Collect-Air XP-67 Moonbat.  Got it around 5 years ago for $150.  It's in stark contrast to all the Monogram kits I have surrounding it which are around $20 or less.    The Moonbat was my one guilty splurge.  When it comes to model kits, I like 'em cheap.

Eric

Full R/C option 1/16th scale Tamiya Tiger I model kit I won in a random drawing at a now-defunct modeling website (kithobbyist.com). It was 11 years ago, and I still haven't gotten around to it.

Original retail price was $1000, but was on sale for $750 (as per the sales invoice that came with the kit). Shipping was free.

I see a couple listed on eBay for $655 + $120 shipping, so the price has remained about the same in over a decade.

Not my kit, but someone's auction for one just like it:

www.ebay.com/.../160938118985

Most expensive is easy - Fisher's 1/32 F7U-3M Cutlass. Pricey, that...makes any other aircraft I have in the stash look cheap, even the Tamiyastangs.

Biggest...well I recently finished HK's B-25, but it was a commission build and so it's no longer with me, but in terms of sheer footprint it was probably the biggest. Outside of that, my 1/144 Revell of Germany USS Fletcher. One beast of a ship.

Largest and most expensive is my Trumpeter 1/16 King Tiger.

Modelsvit 1/72 Antonov An-124 for size and price. Next would probably be tied between the old Aurora Screwdriver Assy. 1/32 B-25 and Eldon 3D Moon Survey, with the B-25 the larger of those two.

The 1/32 Trumpeter Su-27B that I bought from a store in Philadelphia is hands-down the most expensive, and largest, kit in my stash.  

most expensive 1/72 hobbyboss DORA rr gun

largest DORA or trumpeter 1/35 K5 rr gun or revell 1/96 PEDRO NUNES 3 masted barque.

This kit is the smallest in  SCALE   I intend to build BUT it is the LARGEST in physical size.  34 inches.

The biggest kit in my stash has got to be my Tamiya 1/350 Big E Enterprise at just over a metre long. Most expensive is the new Tamiya 1/350 Yamato. She'll kill me when she finds out!!!!!

Jockster

Oh, I forgot about my wood HMS Victory,1.25 metres long aaand most expensive rolled into one. Think I'd better cut up my credit card now!!!!

The most expensive kit I have is the resin 1/220 Kotobukiya Buran, from the "Goiken-Muyo Abunai Mechanics Series"(!).  I think it was something like 22,000 Yen ($275 USD in today's money, a lot less when I bought it.)  The only other kit I have in that price range is the Accurate Armour T28 super heavy tank ($200), seemingly rendered redundant (maybe, maybe not) by the DML plastic kit.

The biggest model I have is the 1/144 Bandai HGUC Dendrobium, which is something like 39 inches long.  It is too wide to fit into my display case, so it never got finished.

I think the title of biggest, most expensive plastic kit must go to the Soar Art 1/35 Dora rail gun.  A friend bought one and said that the box was almost too heavy to carry into the house!  What the heck are we thinking when we buy stuff like that?

Yeah the kit in the box of the Dora weighs 56 pounds.

Most expensive would have to be either Tamiya's (original) 1/350 HIJMS Yamato, or the Aoshima 1/350 HIJMS Maya-1944 fit. Both were purchased on sale at LHSs and even on sale cost over $80 each.

My largest in the stash has to be the Revell 1/48 B-1, with the Monogram B-29 a close second... The biggest built so far are the old Dragon 1/35 SS-1 Scud on TEL, Monogram 1/48 B-17G, and Academy 1/350 Graf Spee.

My largest and most expensive is probably my 1/200th IJNS YAMATO by Nichimo and nearly 5 feet long and nearly $800.00.  I was in Tokyo in 1982 and paid around $50.00 for it.

Aircraft kit would be Tamiya's 1/32nd F-15 for most expensive, Monogram 1/72nd B-36 for largest.

This one is pretty big and cost about a C note!  i235.photobucket.com/.../2008_0131Spock0123.jpg

 Biggest at a little over 3 feet long, and most expensive ($75 for the kit and around $50 in accessories) would be the Polar Lights 1/350 Refit Enterprise. That kit's been out.....what-8 years now?  Still not quite ready to assemble it.  Soon!  ;)