Price is something I really struggle with online. In Florida we have a lot of shows and some stuff I can get at shows cheaper than online and vice versa. That price for a pied female I'd call "fair" but I would pass on that one. Partly because I'd rather have a more significant amount of white and have it be more obvious it's a pied (if you try to sell her down the road you will most likely get less than a high white), but I'd also just rather take another route to pieds (which I'm actually doing). I can get het pieds at shows for $50 very easily, so I'd rather buy like 4 het pied females and then in a year or so I'd buy a male (I bet you can find pied males later this year for 200) and then breed. If you buy a pied male and pied female like this you'll probably end 2016 with 1.1 pieds and you'll have to pray that she'll be up to size and ready to go in a year. If she decides she wants nothing to do with the male, or she goes off feed too often, then you're screwed. But if you have 4 het pied females it's a better chance to having consistent clutches. I'd rather take 50% chance of getting a pied on 4 clutches than 100% chance on 1. That's of course if you want and can handle twice the snakes. If you don't have the room and are fine waiting if she doesn't go then a pied female is fine.
I personally do have a pied female, but I also have 2 het pied females just in case. I paid 360 (Tampa Repticon) for my pied girl last year and she was ~400g.