I'm really not sure about the second set on cards. But. I know something about the unpainted and silver variants for the first set of figures. The unpainted is a variant included in retailers' boxes, each of them got 15 blind boxed-figures, and since the full first set is of 7+1 secret (masked Raiden), the full box gives 7+1 figures of a set and 7 of the other one, example 7+1 colored and 7 unpainted or vice-versa (so basically it's necessary to look for one more figure to get the full 7+1 sets).
About the silver variant figures, i don't remember very well but i got mine from solidsnake1mgs (his Ebay ID - I'm sure some of you remember about him, he was some British old-time MGS collector which sold away his collection time ago, as side note if i don't remember wrong his old site is still accessible on the free domain host - he had many infos about MGS cards and a famous MGS fan-artwork in main page), I just know it's some limited and early edition but I can't recall more... though probably solidsnake1mgs on Ebay might remember some more details about them
Ah and so far (since 3-4 years or so) I've seen the bronze figures only by one or two sellers on Ebay - never running out of them
