Max Keyboards has them. Select "6.0× Spacebar bottom". Then select a style ("Keycap Option").
However... by just installing the keycaps, the Command and Option keys have the reverse meaning.
I don't know if the BW Elite allows you to swap the meaning of the keys on the keyboard, but I have heard that some version of Razer Synapse for Mac should support swapping them.
Otherwise you should be able to swap the keys in System Preferences→ Keyboard → Modifier Keys... but then the keys would be swapped for
all keyboards that you connect ... including the built-in keyboard if you are using a laptop. :-þ
BTW. Some narrow-minded people call keyboards with that width of modifier keys on the bottom row as "non-standard". It is
a standard, and quite a few keyboard, even mechanical ones, do have that configuration.
Some mechanical Razer keyboards do have slightly different mounts for the
space bar though.