Need a player to sit in my car used primarily for audiobooks, some help?

[Xandal]

I'm not super familiar with all of the different sources as I've primarily used my phone and iPods.  I need some help finding a source that works well for audiobooks primarily.  I spend a LOT of time in my car (delivery driver), so I can get through an audiobook in about 3 days.  It's becoming a hassle to keep using CDs from the library, so I am looking around for a source that meets a few requirements.  I do not use audible and don't have to worry about DRM - All my audiobooks are just mp3 files.

1 - Decent storage - Ideally with an SD card expansion slot.
2 - Not too expensive - I plan on leaving this in my car almost 24/7 so I'd rather it not cost a lot if it happens to get stolen (it won't be in plain sight)
3 - Good playlist support or organizational structure so I can keep all the books separate.
4 - FLAC support would be nice (since I'd also like it for some music and my music is in FLAC).  This isn't necessary, but I'd like it.

Battery life is almost irrelevant as it'll be plugged into a charger constantly.  Also, if this matters, it'll be in my car during really cold weather as well as really hot and humid weather (northeast USA).

Any suggestions are really appreciated! Thank you!

 

[Raketen]

Considered just getting a cheap/used smartphone and a good playback app? Can often get region/carrier locked ones for muchlower prices as well.
Sansa Clips have audiobook/podcast support i believe... I've only really used discontinued clip+ and zip, mostly with rockbox... just make sure newer Sport and Jam models will support file length I think.
Sony A10 Walkman series is more expensive, but it will remember resume place of anything you put in the podcast folder, meets all other requirements except price. oh and no playlist creation on device, and in podcast mode it will stop play after finishing a file.
 
There any Flac players for iPod Touch?
 
Idk about their podcast/book functionality but fiio x1 or m3 both <100 dollars, Tons of bargain players also, like Ruizu x02, newsmy etc... seems reasonably functional from my reading... don't know about podcast/audiobook stuff.
Just make sure it can support long files.