Biggest is the 1/48th scale B-29 followed closely by a 32nd scale F-4 Phantom, a B-17 and B-24 and Lancaster in 48th scale and a Bf-109 and a P-51 and a Hurricane in 24th scale. The most expensive is another 48th scale Tamiya Lancaster followed by a 32nd scale Tamiya P-51.
Build it as the Argo, that should be a real different looking Yamato 
BTW, that’s Star Blazers if anybody asks
The Trumpeter 1/16 T34/85 or the Tamiya 1/32 Spitfire IXc
Largest: 1/350 Minicraft RMS Titanic Ocean Liner - Upgraded “Museum Quality” Issue with Corrections and Photoetched Parts.
It will NEVER get built by me.
Largest: the Revell/Monogram 1/48 B-1. I stil do not have a clue where to put that monster if I build it (fortunatly I have 150+ other kits waiting in the stash)
Most expensive, probably my Azur 1/32 Polikarpov I-16. Not that expensive but I buy all my kits cheap at verndor tables or at sales. For instance, I have paid only € 10,- for the Hasegawa Ki-84 Hayate “visible edition” with PE and white metal. I think the retail price would be much higher.
I to have been working on a monster, 1/35 Dora railway gun. I am about 75% done, but every time I think I am getting ahead I add more scratch builling items that someone has done, and I try to improve mine. As for the cost it was purchase on E-Bay in total for $635. I think this was a great buy.
I know what you’re going through; I’ve been working in the 1/72 scale version of this monster. Though not as wildly detailed and complicated as yours, it is still a long and heavy project. I’ve finally gotten mine to the painting stage.
I have a Lindberg 1/125 Blue Devil Destroyer…rather large. Also have 3 A/C kits that are huge…Revellogram B-29, B-52 with X-15 and B-36…all were kinda expensive BUT…
My most expensive kit was an MPM HE177, with every A/M set made for it…bought it on Ebay for $136.00…still in it`s box, afraid to start construction…[:S]
…Oh…forgot the Revellogram B-1 too…very large kit.
I don’t know if this counts but… I am combining several 35 scale kits together. Trumpeter BR-52, K5 Leopold, Karl Morser with Railway carriages, two gondolas and two flatcars all loaded with various stuff ( Tamiya field kitchen, AA guns and various resin from Black Dog). When finished it will be 12 foot 8 and with figures and extras and a scratch built track I hope to break 10,000 pieces. Price will be close to $750 and three years of enjoyment. Would have liked to go bigger, but ran out of wall.
A pair of Italeri C-130s in 1/48th scale. The Heller Victory in 1/100th comes close. I should mention the Victory was purchased from Model Expo as a close-out item for less than the full-blown retail I paid for one of the C-130s on a binge buy.[00ps]
Mine right now is the 1/48 academy f4b phantom 2 Because I also got the photo etch sets that eduard just came out for it.
I also likem cheap, most of my stash comes from model swap meets… The most expensive has to be the Revival metal bodied Mercedes 163 prewar Grand Prix kit I got as an anniversary gift, about $120. I like smaller scale kits so none of them are particularly big, maybe my vacuform 1/72 TU 22.
Biggest would be the Revell B-1B as well. Most expensive would probably be the Trumpeter F/A-18E. But it came with default VFA-143 decals, so I see that as a win/win considering I transitioned them into that scheme.
I have a few other big kits in the stash like the 1:58 C-130J , and a couple of Monograms vintage bomber kits. Those have always been nice big kits.
I’ll play…
Most expensive: Fine Molds 1/72 Millennium Falcon
Biggest: Polar lights 1/350 USS Enterprise Refit
Funny thing is that I don’t do that much Sci fi. I mostly build 1/48 modern jets.
Biggest in my stash?..Well its not in my “stash” any longer, I built it but now don’t know what to do with it, short of hanging from my hobby room ceiling which I’m not a big fan of… Revell Monogram 1/48 Boeing B-29 “Humpin Honey” . Ha, you can check it out in all it’s glory in this forum, just search “Revell Boeing B-29” to view pictures. Most expensive…so far, gotta be my Academy 1/400 Premium Edition Titanic, ($225) what a super cool kit! Photo-etch, wooden decks and correct bow anchor tub to name a few.
Ok, my turn…
My biggest is Tamiya’s 1/350 USS Missouri and my most expensive is also a Tamiya…a Supermarine Spitfire Mk. IXc in 1/32 with some goodies from Barracuda to go with it! The Spitfire is currently on the bench awaiting its first dabs of glue!
Mine? Most expensive is the Finemolds 1/72 Millenium Falcon. Biggest? Dragon’s 1/72 Saturn V Rocket.
My most expensive is definitely the new tool Yamato. Although I did drop a lot on aftermarket goodies for my Trumpy f-14b. My biggest is either my 1/200 Arizona or 1/350 Nimitz both by trumpy.
Mine would be the Revell 1/72 scale USS Gato fleet submarine.
