How would you price a cloak that allows you to turn into a Gargoyle via Monstrous Physique I for 5 minutes a day divided as you choose into 1 minute segments?
The similar Cloak of the Scuttling Rat is basically the same item (allows you to divide up the duration of the spell as you like, limits you to a single form the spell allows you to assume). It costs 6,000.
I do think that the cloak of the gargoyle should cost more, as it would generally be more useful. Any thoughts? There isn't much to go re: magic item creation formulas.
Multiply the monsters DC by 1000 gps then add it to the rat cloak cost.