I've only ever used the "normal" single- or multi-mode 100/1000/10Gb stuff ... 2) Why are the costs of the SFP modules so different? Here is a generic one: The Cisco ones from FS.com are great ...

a Small Form-factor Pluggable (SFP) module designed for SDI media conversion and/or transport to IP using ST2110 or ST2022-6. Direct Plug-in. Artel's new FiberLink SDI Video-to-ST2110/ST2022-6 ...

With physical dimensions similar to a CFP2 module, it is currently the only form factor that supports both multimode and single mode applications at this link speed, as well as both CDAUI-16 ...