after buying early access games on full price only for them to go on sale for 50% a week later. i am worried about these things so if possible could a dev or someone who knows about this stuff tell me about the plans for this game in terms of money because if it is the same model as minecraft in it being the cheapest it will ever be right now and as more things get added it cost more to buy i will likely buy it tomorrow.
played over 6 hours in the demo nothing left to mine
I don't think that they got a sale planned. The release is at least 6 months ahead, and there's no "special" point in development coming that justifies a sale. In fact - as you were guessing - the game even will get a bit more expensive when more features are added and the game approaches completion. They stated that in one of the friday blogs.
If you like the concept and like to play more, don't hesitate and join a great community There is really no reason to wait, except if you like to wait until the game is more "complete", or multiplayer is more stable (shouldn't be long now).
The game has an alpha discout right now and will get more expensive when released; it most likely won't be cheaper than it already is if it gets a Steam sale. No reason not to start playing now