Back in Stock! Technically RRP but you can't find it anywhere else at this price point besides from HTC themselves, usually out of stock. (And technically discontinued)
The Vive Deluxe Audio Strap is worthwhile upgrade if you own an HTC Vive or any other headset that supports attaching it via a mod (Oculus Quest, Rift S, etc.) Although technically not a 'deal' it's not sold anywhere anymore (discontinued supposedly) and where it is sold, it's at significant mark up ($350 On Amazon) so this is your chance to grab one at regular price before they go out of stock again. HTC has said they stopped making these and they won't be in stock again before but I suppose they still have some left? Just know this might be your last chance to get one as there is no word on if they are still making these or just clearing out inventory.
In terms of mods for other VR headsets such as WMR you can generally find someone who has modeled a 3D print part for attachment or DIY (See Thingiverse for the former). Additionally if you own a Quest or Rift S, Etsy and other store fronts have a lot of people selling quality 3D printed parts for attaching it, or it can be done with velcro/cable ties for a less professional looking but very functional solution.
Have Fun!
Wonder if this is a limited run or not?
Edit: typo