There seem to be a lot of sellers out there selling "rare variant Star wars figures" some of these are indeed rare variations while most are simply a different country of origin mark on the figure.

Some vintage figures do have major variations in paint and mouldings but before buying a rare variant I would suggest doing a bit of research the rebel scum website or the jawa's armoury for weapons are excellent sites and will give most of the information you could want on variations and will also tell you which are the rarer items. You don't want to spend a fortune on a rare figure to find it is very common and not worth the money.