I have bought heaps of DVD's and CD's for my elder kid while I was living in US. They were not cheap and do not want to just throw away. Now my second one is in that age to use all those DVD's but just not able to play them in my BluRay player at home or in player in the car which came with Toyota (brand should be Clarion I think).
Is there any way to use them in the same players without buying another set of cheap crappy players for home and car. Is there any way to upgrade firmware on the players to accept disks from different zones?
When you buy an original disk from a company you pay for it to use personally and you are paying a hefty price to own it. The usability of it shouldn't be bound to the place you live at the moment. If you keep travelling are you suppose to buy the same DVD again and again for different regions. I don't think so. no idea about the legal side of it.
What other people really do with those disks you buy abroad.
CDs are not region locked. If your CDs do not play it has nothing to do with US/Australia and everything to do with them not conforming to the CDDA standard.
From Wikipedia:
DVDs are a different story. I try to only buy players that are region free. First however, you should check for firmware updates for your players as some have region free firmware available that can be installed and will solve the problem.
Blu Rays are almost a lost cause.
The work around for all three (CD Audio, DVD Video, Blu Ray Video) is to rip them using a computer (ALL of the DRM measures have been broken on a PC) and reburn them without DRM. Annoying, but this will always work.