That's why they are selling so cheaply, it's so hard to find any batteries for them.They're pretty much useless for anything other than parts if you don't have the clam shell or Li-Ion packs.Thales killed off all support and parts for them.The accessories are rare and hard to find.Some people still think they are sitting on a goldmine with these radios and want hundreds of dollars for them without being able to even verify if they work!
I see the chargers quite often on Feebay.Those are actually the easiest thing to find.People are dumping them because their batteries no longer hold a charge and getting a new battery from the OEM that supplied them to Thales,or a refurb, is about $160 each if you can get them at all.Some get lucky with buying the used ones if they still have decent life in them.
In the rare case that you find a AA clamshell pack it will probably run you about the same amount or more and the clamshell with alkalines can't supply enough power to operate the radio at the full 5 Watts if you need to transmit.It's limited to 2W max.
Someone on the Thales "yahoo's" group apparently has been successful at hack sawing open the Li-Ion packs and replacing the cells with some new ones and getting them to charge.There was also someone selling the new OEM supplied batteries for around $160,but that place has had issues with scammers so beware.
I have an "original" clip on style audio side connector and original clip on lapel mic that I'm looking to get rid of soon.I may also just get rid of this 503 radio all together along with the AA clamshell and screw on audio side connector,belt clip, box,manual and new wideband antenna. I haven't been all that impressed with these so far,but I haven't decided yet on what I want to do.Still mulling it over.