The title is a bit of a lie, I've spent more on parts before, but it was for investment to complete/sell a set. This is the most expensive and smallest piece I've purchased, just to add to my collection as a single part...

I just purchased a pair of trans clear hands from Germany for $50 USD each, $100 total. Seems a bit absurd to spend $100 on a pair of hands, even if they are rare test strike/special colored parts, but there is nostalgic reasoning behind it.
Ever since I started collecting Lego when I was very young, I've always wanted a fully transparent minifig. That dream still lives on today and with transparent legs, heads and arms able to be found in regular retail sets, the dream is so close to complete. Hands, hips and torsos are among the few missing, hands of which I thought I would NEVER see as a reality. After seeing trans clear hands at the BrickLink store I usually go to for special colored parts, I was ecstatic! I bought a pair almost instantly without thought. Now the life long dream is almost complete, and all I need to wait for are hips and torsos. One day hopefully, patience is a virtue...
If anybody is interested, I'll link the store I got these from below, he seems to only have one pair left, but there is another store in Germany that has another pair for slightly more money.
http://www.bricklink.com/store/home.page?_refreshrnd=193931&p=MAGICBRICKS&itemID=86756094#/shop?o={"sort":9,"desc":1,"itemType":"P","catID":"20"}
Comments
Very cool!
I wonder if this was struck from the same mold as opaque minifigure hands, or if they created a test mold specifically for use with this type of plastic.
@Aanchir It costs quite a bit of money to make a new mold, so my guess is that these were done in the same mold. Lots of pieces are done in test colors, with how often Lego tests colors, it wouldn't be feasible to make new molds all the time.
I've spent over $100 on a single 2x4 brick before. And I've seen parts go for over $500 for prototype bits. Stupid plastic pieces.
DaveE
I think we were told at one point that you're not terribly likely to see a fully transparent minifigure in a set because the plastic used for transparent pieces often "binds" to itself more than ABS plastic elements do. ABS/ABS joints are fine, and ABS/Trans joints are fine, but Trans/Trans is tricky. Hence, the arms and legs are probably a bit stiff on the 'fig shown above.
DaveE
What I'd love to see is LEGO be able to sell test runs. That is, right now, if LEGO churned out a swath of trans-glitter-purple hair elements for testing, they won't sell them. They're for prototypes, and haven't been tested through QA, etc, etc. So some of them make their way among internal folks at LEGO, and occasionally (through some sort of backdoor shenanigans) out to BrickLink sellers like Magic Bricks.
But what would be cool is if they sold leftover boxes of prototype stuff to fans to distribute for resale, or to be given away at events (or what-have-you). IE, some sort of more "approved" process to get them into the hands of fans.
As it stands, I don't know how many of these things are floating around at LEGO, unloved. I'm not sure when "Sea-Tron" was being developed, but I know that the batch of cool stuff we got in 2003 included a Sea-Tron figure, which must have been lying around LEGO's offices for at least 15 years. Is there a box somewhere full of them? Are they just here in drips and drabs? I'm not sure. But it'd be neat to see them get out legitimately.
DaveE
and yeah, that's what I thought, there was something like that in illegal connections.
I thought you had just taken that picture.
If I can get a better picture at some point, I'll give it a go. We hesitated taking pictures back then, because we were told to keep it on the down-low. But that was 13 years ago, so we're probably good by now!
DaveE
I'm reviewing mentally all the sets I've bought off eBay or other sellers for much more than MSRP (these are sets almost two decades gone from shelves, mind you), and thinking if I divided the price I paid by the number of pieces in the set, I might have paid a higher amount per piece, but then again, I've never gotten quite that extravagant.
for the incredibly affordable price of 336 Euros!
Yes, all parts that you need for a clear trans minifig is out there. Unfortunaly I was too late as my source had sold them all. But they used be quite common, as in certain employees could pick them up for a penny ;)
The "secret source" that Davee123 is talking about. That's Billund. You may have heard that word before ..
That's correct. I broke one of my prototype hands (it's a hand with a sort of glove on it - never released in any set/minfig) while stuffing it into one of trans arms .. arghh
While I don't have any trans bodies, just sticking those trans legs into a trans brick feels VERY different compared to a normal brick. Well sticking any trans into another trans part feels the same ..
Clear LEGO parts are some sort of polycarbonate, not ABS, and it's quite a different. Not nearly as flexible and it likes to 'bond', for lack of better words
So until TLG finds another way to make clear parts, I don't think we'll see a clear minifig anytime soon. Allthough I did notice those fancy new spooky legs from the latets Ninjago wave don't seem to stick ... hmm
This is also why a transparent 1x1 cone attached to a lightsaber blade is so difficult to get unstuck, but a solid-colored 1x1 cone attached to a lightsaber blade is fine. The former combination is two PC parts, the latter is an ABS part and a PC part. LEGO considers the former an "illegal connection" and tries to avoid it in sets, so they don't instruct kids to do something they can't undo.
From what this says, polycarbonate is actually a stronger plastic, I always thought it was more brittle...
Polycarbonate is second to none when it comes to the impact resistance of plastics - it doesn't need to be very thick to be bulletproof. No, a LEGO windscreen probably isn't thick enough!
ABS isn't too far behind - but it's cheaper.
Something that has very little resistance is acrylic, so it may come down to confusion of types of plastic.