Good question!
Unfortunately, there hasn't been a lot of information released yet about the cost of the Apple VR, since it won't be available until late 2021. Based on Apple's previous product prices, analysts have speculated that the cost could range anywhere from the low hundreds to over a thousand.
However, given the complexity, high quality design, and learning curve of virtual reality headsets like the Apple VR, the final cost could be much higher. Ultimately, the price of the headset will depend on the features and technology Apple is able to include inside the device.
For now, the best way to get an idea of the estimated cost of the Apple VR is to check out the prices of similar devices. You can find out the prices of a variety of different virtual reality headsets here: https://www.engadget.com/topics/vr/headset/. Additionally, it's also worth keeping an eye on any news and updates released by Apple as the year progresses.
Hope that helps!