We have used optics from fs.com with very good luck. In Catalyst, Meraki, Brocade, and a few others. We always buy one set of Cisco branded optics we can use if necessary to rule out an optic issue if problems arise and for Merki support if we need it. Otherwise save yourself some money. As much as I like Cisco these branded optics sold at insane markups are like the old factory floormats in cars. The same company in China makes them all, the only difference is the label on them and some firmware code.