Anywhere from about $700 to about $1,500, depending.
Depending on what?
It's worth more in the People's Republic of California or Massachusetts. It's worth more with the original box and papers, including receipt. It's worth more to collectors for being unfired, but only a little more to shooters, since there are plenty of Pythons on the market, the vast majority of which are good shooters. It's probably worth less if there are lots of used gun and pawn shops in your area. If it were older, it would be worth more, but only to those who know the difference. It's worth more to someone who's desperate for that barrel length with that finish in top condition, but less to someone who already has one.
Blue Book values often don't help a lot with Pythons, because a.) their prices are skyrocketing, and b.) there are so many floating variables at work. The auction sites aren't going to prove very useful, since they're packed to the rafters with sucker prices for Pythons.
If I were looking for a six-inch Python in top-top condition, I'd offer a stranger $800 and see whether it proved enough. I'd be willing to go to about $1,000—or would be, if I weren't looking for a stainless Python with a 2.5-inch barrel. If and/or when I find it, it's going to set me back rather more than that, I'm afraid.