CDE WMF-series caps

[EFK]

I'm having a hard time interpreting finding the data sheets on these - two questions:

1, are these *real* polyester and foil wound/wrapped caps as opposed to metallized polyester? and

2, why are they so darned expensive?

Just curious.

[diagrammatiks]

looks like they are film foil construction

are they that expensive? 2-3 dollars for coupling cap values?

[Jazz P Bass]

The WMF series caps where made for high surge current.
Is this applicable to a tube amp coupling cap?