Quote Originally Posted by Complete Arcane p.161
Spellstitched creatures can be created only by a wizard or sorcerer with the Craft Wondrous Item feat and of sufficient level to cast the spells to be imbued within the undead’s body. The creation process takes a number of days equal to the Wisdom score of the undead creature being spellstitched (so a minimum of 10 days) and requires the expenditure of 1,000 gp for carving or tattooing materials in addition to 500 XP × the undead creature’s Wisdom score.
So from this we know
1. Spellstitched Undead costs only 1000gp
2. You don't need to know the spells to be stitched. You only need to be of sufficient level.

This is pretty amazing on sorcerers who can spellstitch themselves.