You only need to buy the base game to get all the PU stuff including the ability to trade / fight and get more credits to purchase different things... apart from the special variants currently, all ships are purchasable in game. The other ships you see not in starter packs are for those people who wish to support the game. Essentially you're backing the development with a contribution, and in return you get a digital ship plus some insurance. All 'pledges' are basically just backing development. There are a lot of people who clearly see this as something worth investing in, myself included.
I sold out and got a full refund in 2018 about the release of Alpha 2.6, closed my account which I had since 2012 and had spent ~$1000NZD... since Alpha 3.0 I've got back in to it and now have spent a bit more than I had originally, but its all disposable to me and if this gets anywhere near its potential then it will be great... Sure its slow, I don't think anyone can argue that, and the scope has been stretched (at backers request during hte original kickstart) but the bed to space to planet, at scale, approach is pretty cool and it will get better as they resolve the server meshing.
I sold out and got a full refund in 2018 about the release of Alpha 2.6, closed my account which I had since 2012 and had spent ~$1000NZD... since Alpha 3.0 I've got back in to it and now have spent a bit more than I had originally, but its all disposable to me and if this gets anywhere near its potential then it will be great... Sure its slow, I don't think anyone can argue that, and the scope has been stretched (at backers request during hte original kickstart) but the bed to space to planet, at scale, approach is pretty cool and it will get better as they resolve the server meshing.