Here is some other info that is partially related. For those converting the black plastics on the seats, the part number and prices (Mazdacomp) are listed below. I haven't actually ordered the parts but as best as i can tell these are correct. All parts are black (code 02 at the end)

FD01-88-1G5 -02 - RT reclining handle $7.20
FD01-88-1H5 -02 - LT reclining handle $7.20
FD01-88-1G1 -02 - Rt side plastic cover $27.45
FD01-88-1H3 -02 - Lt side plastic cover $27.45
FD01-68-6F6A-02 - cover for hatch/fuel lever $25.20 (this one maybe in question)
FD01-88-162 - Seat cushion replacement $61.65

As you can see it will be cheaper to dye/paint them...however if you are worried about wear these may be an alternative.

Add one more to the mix: Me!

And here's my price schedule:

Parts covered in Milano (8 oz.) Ultrasuede Brand, choice of 48 colors. Black, red, grey or white thread colors:

Entire seat, front & back, OEM pattern, choice of up to two colors, $1600.00 per pair*

Seat center sections only, OEM pattern, one color, $800.00 per pair

**"Porsche" style ribs, add $50.00 per pair.

Add 1/2" EAR Specialty Composites visco elastic memory foam to center seat surfaces, $100.00 per pair

Replace bottom center foam and side bolsters with Mazda OEM on driver’s seat only , passenger side N/A, $150.00

*Includes minor repairs to seat fasteners if needed, choice of thread color, Porsche style ribs if desired.

** "Porsche" style ribs includes 6, 1 inch ribs in the butt and lumbar portions of the seat. These ribs effectively
make the seat deeper and give you a little more leg and head room, it also tends to give you more lumbar support since your spine is curved a little more. You’ll feel more “tucked in” to the seat, but it is not quite as cushy.
Recommended for drivers 6’ tall and over.

Seat covers must be removed from the frames and received in one piece. You will need hog ring pliers and hog rings to reinstall the covers - available at any quality hardware store. Any hidden damage like ripped support fabric or broken plastic fasteners will be repaired at an additional $75.00 per hour plus materials. Most driver’s seats have minor hidden damage to the underlying support attachments which is easily repaired. The bottom foam and side bolsters on the driver’s side are usually worn out and I strongly recommend that they should be replaced for maximum comfort and to give your seat a “like new“ OEM feeling and look.