We already sabotage ourselves in astronomy by refraining from mass production approaches for political reasons.
There is no practical amount of fuel that can get you to 500AU on a simple trajectory. What seems to be the best option for setting massive vehicles on a solar escape is a sequence that looks something like:
* Launching to Jupiter propulsively
* Cancelling out most solar-orbital velocity there using a gravity assist in order to dive down into a sun-skimming orbit
* Burning through a large solid state rocket kick stage while at close approach to the sun from behind a heat shield. The Oberth Maneuver.
* (optional) unfurling an electric sail or solar sail once the rocket has finished as you're speeding away from Sol
Together that gets you the required ~100AU/year escape for a mass fraction that is tractable for our civilization.