Do you do discounts? Also what's the difference between $30 and $45?
Can't say about discounts, sorry. No clue. For the prices though:
The $29.99 USD one is a pre-order, you pay for it now and get the game when it comes out fully. the $45 USD one has beta access, which allows you to play the game as it's being built.
Thing is, since the latter is still early access, it's only got two routes complete so far, and is rife with glitches and problems. Thankfully, you can email the developer with the glitches you've found, and they can release patches for these problems thanks to all us players' help.