I did find ads for replacement back panels with a new plastic or glass window but those were also relatively expensive.
Miata door window replacement.
Use white lithium grease.
This repair may be undertaken by any careful moderately experienced diy mechanic although it involves trim that requires care to replace neatly.
It may not be necessary to remove the door panel to do an adequate job.
Any of these problems the same door and window disassembly is required.
Later models may require a different method.
Mazda sells a replacement back window for 370 and that is just for the clear plastic part you then need to take it to a shop to have it installed.
The inner panel shown is for a miata with manual windows.
This is a typical miata door assembly.
On the lower exterior is a single weatherstrippingwhich keeps water out of the door protecting interior components of the door from wind and weather and creating an aesthetic appearance at the lower edge of the window.
A catalog sells replacement plastic back panels for 170 and glass back panels.
Lubricating miata door windows lubricating the door window channels can make the windows roll up and down more easily and can prevent future problems with the mechanism or cable.
Note that not all miata s will have the same door panel some earlier models may not have the.