We (finally) increased the price for the first time, from $9.99 to $14.99. Originally we had planned to do this in fall 2016 but for various reasons we waited a little longer. The Early Access section of the Steam Store page still has the announcement from October 2016 where we said we'll go from $9.99 to $14.99 "shortly".
We'll stay at $14.99 for a little while until Holodance is feature complete (this in particular means you can play story-mode from beginning to end). At that point in time, it will go up to $19.99.
Once we officially release Holodance, it will have its final price, which will be either $24.99 or $29.99, depending on how much we put into the game by then (a lot of what you already see in the current version of the game was originally planned for "Episode 2" which would have been a separate game ... it turned out during development that we should have started with "Episode 2" but that's history, now we'll just have Holodance with "story-mode" and "free-mode" ;-) ).
One option we're also considering is keeping the price of the game itself a little lower (maybe even $19.99 which is what we had originally planned), and focus more on paid DLC after release.
From the beginning, we planned to have "musical theme packs" which will be packs of 11 or more songs specifically composed / produced for the levels of story-mode (for level 12, we have something fairly special planned I'd rather not promise that each musical theme pack will provide a song that properly fits that even though some may, also a pack could provide multiple songs for one level). I have already talked to a few musicians / producers about creating packs in different genres but obviously, this can only start when story-mode is complete. Those will be $9.99, with 50% of what we get going to the artist (so the idea is to also make this a platform for musicians / producers to get their music in a high-quality VR rhythm game and earn a little money that way).
A fairly new idea is having additional avatars to the upcoming avatar system also as paid DLC. So you would of course get a decent selection, including customization options as part of the game. But in addition, there could be fancy extra avatars that you buy e.g. for $2 or $3 each.
Environments as paid DLC have been suggested by players but currently my feeling is that environments, just like custom ScoreHUDs or custom orb themes are things that are better handled by Steam Workshop, so those would be created and shared by the community.
Let us know what you think in the comments!