Have a ZX300 in very good condition. I've always used case and screen protector (perfectly applied... you can barely tell its there from pictures).
A Musashino label case is included, it costs $75 from Japan. The battery is very strong, at least 20 hours playing 44khz flac.
This is a well-balanced player- compact and easy to use, warm and musical sound quality, and the 4.4mm balanced output has plenty of drive.