On that previous question the product is a Pioneer PD-M910

Unfortunately t isn't available anywhere. If it was, this link would find it.

https://www.google.com/search?q=%22PIONEER+PD-M6%22+replacement+magazine

..

DIRECT LINK FREE COPY YOURS http://www.filestube.com/p/pioneer+pd+f908+manual

http://www.pioneer.eu/eur/support/manuals/PD-F1007/index.html

CDs go in the Upside Down position. Your PD M501 will accept PRW 1139, PRW 1141 and 163.
Lexus Models: CDX-M9071zt CDX-M8036, CDX-M9071, CDX-M9741, CDX-M9751
also:
Philips CDC-875 Pioneer CDX-FM35 Pioneer CDX-FM45 Pioneer CDX-M30 Pioneer CDX-M40 Pioneer PD-DM802

* Pioneer PD-DM902 Pioneer PD-M403 Pioneer PD-M423 Pioneer PD-M426 Pioneer PD-M450 PD-M453 PD-M455
* Pioneer PD-M501 Pioneer PD-M502 PD-M503 Pioneer PD-M510 Pioneer PD-M530 Pioneer PD-M550 Pioneer PD-M552 Pioneer
* PD-M600 PD-M601 PD-M603 Pioneer PD-M610 Pioneer PD-M630 Pioneer PD-M650
* Pioneer PD-M701 Pioneer PD-M702 Pioneer PD-M703 Pioneer PD-M710 Pioneer PD-M730
* Pioneer PD-M801 Pioneer PD-TM1 Pioneer PD-TM2 Pioneer PD-TM3 Pioneer CCS-430
* DCM-444 and DCM 777

BMW 740 OEM

The standard cartridge for the Pioneer PD-M501 is the Pioneer JD-M300 6-disc magazine, and you can find them at Amazon.com for $25 new. The JD-M300 fits a lot of different brands of CD players, not just this particular brand and model. And here's a link to a copy of the owner's manual: http://www.scribd.com/doc/22613342/Pioneer-PD-M601-M551-M501

Sometimes the little ball bearings that keep the cart trays separated come out causing tray jams.
Make sure your tray retracts all the way into the player flush with the face plate, gently push it in while retracting for those occasional no-read situations. (Also for Denon that takes these same carts). Also note that the CDs go in the Upside Down position.
Applicable to:
Lexus Models: CDX-M9071zt CDX-M8036, CDX-M9071, CDX-M9741, CDX-M9751
also:
Philips CDC-875 Pioneer CDX-FM35 Pioneer CDX-FM45 Pioneer CDX-M30 Pioneer CDX-M40 Pioneer PD-DM802

* Pioneer PD-DM902 Pioneer PD-M403 Pioneer PD-M423 Pioneer PD-M426 Pioneer PD-M450 PD-M453 PD-M455
* Pioneer PD-M501 Pioneer PD-M502 PD-M503 Pioneer PD-M510 Pioneer PD-M530 Pioneer PD-M550 Pioneer PD-M552 Pioneer
* PD-M600 PD-M601 PD-M603 Pioneer PD-M610 Pioneer PD-M630 Pioneer PD-M650
* Pioneer PD-M701 Pioneer PD-M702 Pioneer PD-M703 Pioneer PD-M710 Pioneer PD-M730
* Pioneer PD-M801 Pioneer PD-TM1 Pioneer PD-TM2 Pioneer PD-TM3 Pioneer CCS-430
* DCM-444 and DCM 777

BMW 740 OEM and others.

With the top off the unit, you can turn the tray gears manually for slow eject function. Unplug unit before touching anything inside, check internal fuses.
Sometimes the little ball bearings that keep the cart trays separated come out causing tray jams and shorts.
Make sure your tray retracts all the way into the player flush with the face plate when loading, gently push it in while retracting for those occasional no-read situations. (Also for Denon that takes these same carts). Also note that the CDs go in the Upside Down position.
Applicable to:
Lexus Models: CDX-M9071zt CDX-M8036, CDX-M9071, CDX-M9741, CDX-M9751
also:
Philips CDC-875 Pioneer CDX-FM35 Pioneer CDX-FM45 Pioneer CDX-M30 Pioneer CDX-M40 Pioneer PD-DM802

* Pioneer PD-DM902 Pioneer PD-M403 Pioneer PD-M423 Pioneer PD-M426 Pioneer PD-M450 PD-M453 PD-M455
* Pioneer PD-M501 Pioneer PD-M502 PD-M503 Pioneer PD-M510 Pioneer PD-M530 Pioneer PD-M550 Pioneer PD-M552 Pioneer
* PD-M600 PD-M601 PD-M603 Pioneer PD-M610 Pioneer PD-M630 Pioneer PD-M650
* Pioneer PD-M701 Pioneer PD-M702 Pioneer PD-M703 Pioneer PD-M710 Pioneer PD-M730
* Pioneer PD-M801 Pioneer PD-TM1 Pioneer PD-TM2 Pioneer PD-TM3 Pioneer CCS-430
* DCM-444 and DCM 777
Many Magnavox, Denon, JVC,
BMW 740 OEM and others.

https://www.manualowl.com/m/Pioneer/PD-F908/Manual/258600

They are very rare nowadays. I would try music stores, but be prepared to spend some bucks if they carry them. In canada they cost $50 for a set of 3.
Your best bet, and also inexpensive, is to search on Craigslist.com or Kijiji.com, where people sell/trade/barter their unwanted, unused stuff.
Enter PD-M 430 CD and you may find related products. If that fails, try CD MAGAZINES. Be creative and you may find them.

Good luck!