I retired my hw700ds several years ago. Battery is hard wired. Had to break out the solder iron to replace them once. Didn't want to go through that a second time. Also, iirc the passthru did not support 4k.
The two "cheap" alternatives right now are the Senn rs-175s for about $200, or the Sony WH-L600 for about $300.
In the near future, Creative will be releasing the SXFI TV. That is the one I have been waiting on, but they have been delayed over a year, so who knows. I expect them to be around $300.
The upcoming JVC Exofield system for around $1,000 looks promising, but would like to hear it myself before investing that much.