Your search for "QSFP-40G-SM4" revealed the following:
Dell QSFP-40G-SM4 77KC3 40GB BASE-SR4 850nm MMF QSFP+ Transceiver
SKU: NSB-5946
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days
$ 64.99
• Only 2 remaining
Call if you need more
NEW Dell QSFP-40G-SM4 77KC3 40GB BASE-SR4 850nm MMF QSFP+ Transceiver
SKU: NSN-0837
Condition: New
Shipping: Overnight Options
Warranty: 365 days
$ 68.99
• Only 2 remaining
Call if you need more