Ever buy a whole kit for a tiny bit?

[Flyer]

I have not intentionally purchased a kit for a particular bit, I have however purchased plenty of random kits that I will only be using bits of... 

[The Wooksta!]

I have.
Spitfires.
The 2009 AZ mk I tooling had a speciftic part for the PR.Ig, a bulged camera door that was handy for other Spitfires. It didn't matter as I still had another Spitfire.
Ditto the Airfix IIa boxing for the mk V oil cooler.

There's a few resin conversions I'd bought for the one part, just recently the Freightdog Lightning FGA conversion just for the belly fairings I can do the RAAF two seater.

[Steel Penguin]

a glazing less 2nd hand 1:48 revel B1 kit for the rotary launchers and munitions,  I was then going to scrap the rest, but mrs SP said " build it as a set of crashed and ruined scenery pieces, so it got bagged and put in the loft 

[loupgarou]

My ongoing Shackleton build is obviously heavily dependent on the engines and stabilisators furnished via the 1/96 ex-Frog Britannia in bought specifically for this purpose.
Usually, I have to admit I'm not entirely comfortable doing this as I prefer to build something from everything. But sometimes, you have to do what you have to do..

The Britannia fuselage could be useful for a scaleoramed 1/72 smaller airliner, De Havilland Heron class, for example. 

[Mossie]

I've bought more than one kit for the decals with no firm plans for the kit.  Airfix 1/72 Lynx HMA.8 for the Brazilian Navy decals, never got around to whatever I planned, and can't remember what it was.  Italeri 1/72 F-16 that donated it's Venezuelan markings to a Hasegawa F-16 Egg Plane.

[Flyer]

I have not intentionally purchased a kit for a particular bit, I have however purchased plenty of random kits that I will only be using bits of... 

Realized that is not actually true, I have purchased three Airfix Fw-190 A-8's in the past with the aim of just using the engine, cowl and prop on a Ca-13, had a failed attempt at it year's ago and picked up a couple more 190's for when I got hold of some more Ca-13's then forgot about it until Old Wombat  built his Sea Wallaby, then forgot about it again but for some unknown reason remembered again last night. 

[NARSES2]

I've bought more than one kit for the decals with no firm plans for the kit. 

I've done that a few times

[DogfighterZen]

Yup... done that a few times before myself...  bought a few F-16 kits just because of the conformal fuel tanks or a specific fin base i need for use on other kits. Bought the AFV Club 1/48 RF-5E i'm building for the ongoing Recce GB to steal the late type LERX and shark nose parts to use on another AFV Club F-5 kit. Bought the Special hobby Mirage F-1AZ/CZ just because of the different nose.

[Gondor]

My buying a whole kit just to get one option which lead sandiego89 to start this thread is not the first time I have done similar things. I also don't like to waste parts from kits, my increasing collection of spares is testament to that. I have bought kits just for decal options, the Italeri F-111A for example has the best set of decals for an F-111A used in Vietnam although the decals will be eventually going onto a Hasegawa kit that's in the stash, no idea what's happening to the Italeri kit at the moment. Starting to think I need to keep better notes of what I have planed for each kit and become less haphazard to my record keeping, probably not going to happen though.
Back to the thread title though, buying a kit for just one piece? No, a selection of pieces yes, but just one, no.

Gondor

[Hobbes]

My scratchbuilds have eaten a few kits:
- Revell Challenger 604 cockpit glazing (Sentinel R.1)
- Revell Fokker 100 engines (also Sentinel R.1)
- Mikro-Mir Victor: 4 main wheels (HP.111, along with another Victor for the wings, tailplanes and u/c)

[zenrat]

My scratchbuilds have eaten a few kits:
- Revell Challenger 604 cockpit glazing (Sentinel R.1)
- Revell Fokker 100 engines (also Sentinel R.1)
- Mikro-Mir Victor: 4 main wheels (HP.111, along with another Victor for the wings, tailplanes and u/c)

But did you rob the parts from kits you already had, or did you buy them specifically to get those parts?

Not that it matters.  What matters is what you do with what is left.
If you pack it up and sell it as "probably complete" then you are a very bad person.

[Hobbes]

What's left stays in the stash for future builds.

[Gondor]

What's left stays in the stash for future builds.

Agreed, you never know when you might need a shape or part that is in the robbed parts pile.

Gondor

[NARSES2]

What's left stays in the stash for future builds.

Agreed, you never know when you might need a shape or part that is in the robbed parts pile.

Gondor

As long as you can remember which box it's in. My spares boxes are all "clearly" marked, but I obviously need to re-think my current system after some rather extended searching last week. I got there, but it took some time.

[McColm]

The 1/72 Italeri Sikorsky UH-60 Desert Hawk has been very useful in supplying parts for my Italeri EH-101 Cormorant (UH-71 Kestrel).