Hi, Hermes. Are you remembering this, which I posted back in 2012?
Quote:
"The Marshall will assess any form for magical armour or weaponry at 2,000-24,000 florins above its base (unenchanted) value. This is because an experienced warrior can tell quite quickly if a suit of armour or a sword-blade is enchanted, but he cannot easily determine how enchanted."
So, there you go - the cost of a magical sword is 30 + (2d12x1000) florins. If there's enough of them going around, traders probably settle on around 15,000 florins as an agreed selling rate (that is, slightly more than half the standard value), and something much smaller as an agreed buying rate - maybe around 5,000 florins, which is the cost of two warhorses or a large townhouse.
Personally, I reckon the price should be something that money can't buy - it's a sword with an angel trapped in it, after all.
And since the angel is trapped because they made a commitment to the greater good that proved to come with a personal great cost, I think the price should involve one of the characters having to make a commitment to the greater good that will impose a great personal cost down the track.
Hope this helps,
Gary Johnson