Model 19's are not uncommon, but one "as new," and "in the box" are. You're suggested price of around $325.00 is not out of line, but in some places, for what you want, it could be a bit low. If you drop the "in the box" requirement I think you might be on the high side, but still in the ball park.
All of this presumes you are looking for an older model 19, with the firing pin on the hammer, no "Brady lock," etc.