I'd initially be going for brands that make other quality, well known audio equipment like Fiio & Moondrop (Syitren also seems okay). Outside of that, I'd stay within my price range and make sure the player has CD, CD-R, CD-RW, MP3 and WMA capabilities. Like maybe the Klim Nomad portable CD player.

Also, just looked at the price of the Instant Disk - it's $270aud so you can for sure go the Fiio if that's your price range