Price check on aisle 12! (magic item pricing)

[Nareau]

Since everyone was so helpful with figuring out how much the speed-boosing ioun stone should be worth, I come back seeking your help:

Cloak of the Worm
This brilliant red cloak is made from an extremely light and soft suede. The material is cut from the skin of a Planar Worm. The skin retains a minor connection to the Nessun Dove.
By activating the cloak, the wearer can slip inbetween planes for a moment, allowing them to travel a short distance.
Use Activated
Standard Action
Allows user to teleport per the Dimension Door spell, with the following restrictions:
Range is limited to 50'
Destination must be in line of effect
It can be used only once per day

Nareau

 

[Alchemist]

A good start would be (Ripped from the SRD):

Cape of the Mountebank: On command, this bright red and gold cape allows the wearer to use the magic of the dimension door spell once per day. When he disappears, he leaves behind a cloud of smoke, appearing in a similar fashion at his destination.

Moderate conjuration; CL 9th; Craft Wondrous Item, dimension door; Price 10,080 gp;Weight 1 lb.

DD has a medium range, whereas you only want a short range and line of effect. I would scale the price back to something on the order of 6000gp.