There are many Rubik's Cubes on ebay but many are fakes and are often poor quality and can fall apart after a few turns. Like most things in life you get what you pay for.
How can you tell a fake cube from the genuine item?
The best and simplest rule is 'LOOK FOR THE LOGO'. On all genuine Rubik's cubes there will be a Rubik's logo on one of the white squares, no logo and it's probably a cheap knock off. There were a few cubes that didnot have a logo but unless they are sealed in a plastic clear container it is impossable too tell from a picture whether it is an original or a fake. I wouldn't buy one!
If you cannot see the white side the chances are it does not have the logo, would you take a picture and not show the logo? but you can always ask the seller though, I have seen worse ebay mistakes.
How can you tell a fake Rubik's Magic from the genuine item?
Again LOOK FOR THE LOGO. The original Rubik's Magic was black with 3 coloured rings and comprised of 8 tiles. A year after the RUBIK'S MAGIC the RUBIK'S MASTER MAGIC was released, they are silver with 5 coloured rings and comprise of 12 tilies.
I'm interested in collecting, whats the best way of searching?
Try using the misspellings including RUBIKS, RUBIX, RUBICS, RUBICKS, dont forget too include the correct spelling RUBIK'S and don't include the word cube. because puzzles are quite small and light it is always good tosearch world wide. This should bring you a lot more results.
I hope this guide has been helpfull and PLEASE RATE IT and if you have any questions then please feel free too contact me.