The entire game is based off of player skill, there is no leveling. Also, keep in mind that there isn't really a better ship, just different ones for different purposes. The things that really put a ship up there are all the modules you can buy for it, and those are ONLY available via in game credit (similar to the guns in Planetside 2, except the ships will no longer be available after game launch). Also, say you buy a larger ship, well you better have the people to fly it too, otherwise it's a flying target for pirates. Everything in this game is designed to have specific pros and cons, nothing is better than another unless you're trying to outmaneuver a fighter spacecraft with a salvage ship, or mining asteroids with a racing craft. Everything is designed to level out on the players skill and purpose.
It has been brought up to Chris Robert's (the founder) attention several times, and he has specifically stated that this is not going to be pay to win. The lifetime insurance offered now on ship really doesn't mean much because getting the insurance in game and renewing it for what ever terms you buy it for is easy and cheap, as stated by the developers. People who say this is pay to win are the people that see the ship sale numbers and amount raised, but anyone who has looked into it knows that is far from the case.
Sorry for the rant wall of text, but after spending the amount of money I have spent/plan to spend on this game, I have followed it on a daily basis (I open it up with team9000 everytime I start my browser) and hate it when people misconstrue it.
/rant