OP, you just touched upon this in your last post, but I'd like to address it in detail.
Yes, you are in fact being more principled than is really necessary.
The fight that you would make in paying more attention to your clothes, dishes, and many other items in your life (as far as items that need regular replacement, your clothes would be more than enough) and making sure that they aren't made in sweatshops would yield significantly better results than the fight to buy speedcubes that aren't made in countries that are presumed to operate a high percentage of sweatshops.
Making sure that your speedcubes aren't "sweatshopped" just isn't a battle that is worth it, in terms of the difference in quality (between sweatshopped cubes and those made anywhere that chopsticks aren't de rigeur), and the difference in cost.
By comparison, clothing made pretty much anywhere can be compared to clothing made pretty much anywhere else (aside from high-end junk and blah ****ing blah) so putting your dollars towards fair labor practices re: clothing makes a much bigger difference, both to the financial support you give to fair labor companies (and the dollars you're not putting toward sweatshops), as well as the awareness you're spreading among your friends, family, and peers. When you spread the word about fairly manufactured clothing, those around you take note. You're spreading mindshare, and you're letting people know about clothes (or whatever else).
No one's going to give a damn if you only buy non-Chinese (I'm just singling out China for simplicity) speedcubes. A single "lost" purchase of maybe $20 isn't going to hurt Moyu or Dayan. Buying 5 shirts a year from a good company WILL be noticed, as it helps the company you support and hurts the evil company you ignore.
There is another point here that I'm re-emphasizing that makes all of this ******** kind of moot anyway:
We have no concrete proof that Moyu/Dayan/etc ARE in fact operating a sweatshop. We have no proof that V-Cube DOESN'T in fact have Eponine and her 25 sisters/cousins chained to a wall along with an iPod set to infinite repeat "We Built This City" playing in the background.
Yes, Greece is less known for labor abuse. Yes, China has done ****-all towards dispelling the perception that they do nothing but exploit workers. But we simply don't know in the case of speedcubes which is true and which isn't, aside from going there in person. And the end game difference is maybe $20 at best. How much does a pair of pants that you buy cost, or your belt or shoes? A speedcube can last years, how often do you buy new clothes? THOSE are the companies that will feel the hit.
I highly recommend that as far as speedcubes are concerned, you let it go and just buy a good one from Moyu or Dayan. Just give up this fight, the victory isn't worth it, and set your mind (which is already admirably aware of the main issue at hand) towards other products that are much more salient towards your argument.