Inventory Manager is the latest product from Small Systems Software Development. Designed for businesses that rent equipment by the week or month, this product tracks your inventory, calculates interim and final bills including replacement costs for lost items.
Keep track of customers, jobs, and parts. Set aside inventory for later transfer. Inventory Manager is designed for small to mid sized companies and can be scaled up for large companies if needed. Priced right, too, at only $499 for the registered version that removes the demo limitations.

A demo version is available below. The demo version is fully functional but is limited to 2 customers, 3 sites, and 5 parts.
Here is the pdf documentation,
and Here is the demo.
To purchase the program and remove the limitations, click the button below to purchase via Paypal. Please include information regarding the name of your company (to be at the top of the Billing Report). Customization is also available at modest rates.