You won't find a 'true' 4K player (4096?×?2160) out there for a reasonable amount of $$$. You don't need it, since consumer-level TV's don't support it.
What you will find are 4K-UHD players (3840?×?2160)
I just bought a Sony UDP-X800M2 ($229.00 at Best Buy.)
My 'must have' criteria were:
- Separate HDMI video and audio out. I'll feed the TV and my surround sound receiver separately. My receiver doesn't have 4K pass-through capability, and I don't want to buy a new one yet.
- Ability to play almost all discs (4K UHD, HD Blu-ray, DVD, SACD, DVD-Audio, CD, and others.)
- HDR-10 and Dolby Vision decoders. Unfortunately, this player can't detect DV automatically - it must be menu selected when you play a disc that supports it. I can live with that, and maybe a software update down the road will fix that.) My receiver is 7.1 THX, and will support many of the audio formats available. It doesn't support Dolby Atmos, but that's another limitation that budget forces me to live with. First world problem.
I'll end up with a Smart 4K TV that will stream content and feed an optical digital signal to one of the receiver's inputs, and a 4K player (the Sony) connected to an HDMI input on the TV, sending audio to a second input on the receiver. The only switching I'll have to do is when I want to watch a disc, and then I'll have to switch both the TV and the receiver - oh well.