My most expensive morphs have been pairs: $800 for a gorgeous VPI Axanthic male + het female pair, and $950 for a Red Axanthic male + het red female pair.

I've kicked around the idea of $1000 for a single snake, but I haven't made that jump just yet. I will need a male g-stripe in the next year, though, so that may break my record (though, the g-stripes are really coming down in price).