Idaho Code § 63-3608: Purchase.

The term "purchase" means any transfer, rental, exchange, or barter, conditional or otherwise, in any manner or by any means whatsoever, of tangible personal property for a consideration. A transaction whereby the possession of property is transferred but the seller retains the title as security for the payment of the price is a purchase. A transfer for a consideration of any publication or of tangible personal property which has been produced, fabricated, or printed to the special order of the customer is also a purchase.