Yes, the original trigger was the "A/S" trigger - which is DA/SA. I love the SA pull on it for the range too.
I have seen new ones for $525-$550, and I paid $515 for my compact and $555 for my fullsize. Now, be aware that word is that S&W will not be importing anymore A/S models for several more months. New ones have dried up a bit, and prices have risen a little ($599-$650).
However, I think that is too high for a used one. I think U are right with the price. There are some people online asking those kind of prices for used ones, but I'd never pay that.
Personally, I like the gen 2 and gen 3 frames better than the original style. But, many prefer the gen 1s.