Hey Zepp,
If it's a true vintage, then $10 for a shrink-wrapped model kit is alright. In the mid to late-90's, many of the vintage models were reissued though, in which case the $10 is a so-so price.
I'm not sure if C-3PO was among those reissued. I know when I was just recatching SW fever around '95, I picked up a few vehicle models. I don't have the boxes handy to tell you the difference, but it's not that easy, because they kept the vintage style of packaging. There is some sort of disclaimer on the box that mentions it being a reissue, but it's kinda small.
I suggest looking for a copywrite date on the box. If it's later than late-80's, then it's a reissue.
Barada