See now.. you had to throw a Paladin into the mix didn't you?
It's an evil item, people like a Paladin won't want to let it get out into the general populace. They will want it eithier destroyed so it can do no harm again, or contained so it can't fall into the right hands.
A party can still profit from this though (even good people). Seems to me that a powerful and good aligned church would pay market rates to take this item into their posession. Then they can destroy it, or secure it in a hard to reach place. Since you have a Paladin in your party, his church is a good fit. Perhaps the party can trade it in for an item (or items) of equivalent power that they can use immediately?
I actually think it's more fun if the church can't destory the sword for whatever reason. Have them build a 'remote and forgotten temple with an item of great power hidden inside' and it's that sword. You can make a side project out of it one night. Give your PC's the budget that the church can afford to put into the idea, and then let the players design it. They can fill it full of traps and warnings (so good people don't get hurt and know to just walk away).
Then, in a future campaign, you have a hand designed dungeon crawl for PC's!