I saw an 025 in a pawn shop a while back for $170. Of course I've also seen an 011 in that same pawn shop for $250. (Not kidding.) The 025 is a decent saw, but it's a homeowner's saw. And in that role, it'll work fine for small stuff. If you're going to work it hard day in and day out, and depend on it on a professional level, you'll need to look at an 026/MS260.
The 025 is the MS250 for all intensive purposes. And you won't see any 0XX numbered saw on Stihl's website. In 2001 (I believe it was '01) Stihl swapped their numbering system from 0XX to XX0. The 044 became the 440, the 066 became the 660, and the 025 became the 250 and so on.
Jeff