I much prefer the original Wonder Woman bisho but 1 : it's too expensive now and 2 : the older bishoujos are really small. I got Christie because I really like her (and because it was relatively cheap) but the size difference between the old and new bishoujos is starting to make my collection look odd, so I'll stop here.
The original Wonder Woman is not small. She's the same size as the more recent figures. Exact same size as Power Girl. You're thinking of the really old figures like the first Black Widow and Rogue that came out in 2009, but by 2011 they had increased the size. As for price, look at auctions (not buy it nows) on ebay. They are going for decent prices sometimes. Though most of these are US auctions, so maybe not such a good option for you.