Your search for "ex4500-lb" revealed the following:
NEW Juniper EX4500-LB EX4500 Series Intraconnect Plug-In Board Switch Module
SKU: NSN-7782
Condition: New
Shipping: Overnight Options
Warranty: 365 days
$ 411.99
• Only 1 remaining
Call if you need more
Juniper EX4500-LB EX4500 Series Intraconnect Plug-In Board Switch Module
SKU: NSH-6248
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 105.99
• Only 2 remaining
Call if you need more