I don't know how complete it is but price wise, I think the next big Steam sale isn't until the end of October. If you could wait until then, you might not only get a better price but since the game just released on Steam on August 21, that would also give them some more time for QA if needed.
I read a post from the devs that early access is being offered "at a reduced price" so I expect it'll be at least $50, or even $60 instead of $40 when it gets to release. The only way you're going to get it cheaper is IF it goes on sale with a steam sale, which isn't guaranteed.
That said the game is buggy as heck right now, lots of crashes and some game breaking bugs like siege of forts being completely broken. Devs are working on fixing it, but it's not like release is going to be in the next couple of weeks so you can probably afford to hold off and see what the game looks like after a couple rounds of bugfix patches