I'm not keen on using Bluff or Diplomacy rolls on PCs - I prefer to look at the NPC's skills & if they're high, I play them as persuasive, but it's up to the PC.
I use Market Price for magic items not as a catalogue price, but more the way Neverwinter Nights does - as a rough mid-point between the easy-sell price (50%) and the easy-buy price (200-400%). Market price reflects the actual difficulty of making an item and is what the selling & buying prices gravitate towards. In a notional perfect economy with 100% availability of all items, everything would be bought & sold at the market price.
As it is, adventurers selling loot get at least 1/2 market price, but can use Gather Information to get closer to the market price. Buying, they pay at most 400% market price but can use gather information, friendly contacts, diplomacy etc to get magic for closer to the market price.
Professional merchants - including wizards making items for sale - get at least market price. A wizard making goods for a Duke will receive market price from his liege. But he can use gather info & other skills to get more, up to around x4, or whatever people will pay.
Some common magic items have actual market competition and can be bought for closer to market price, eg cure potions. Very rare items or needed spells may cost much more than even x4 base to acquire - a resurrection spell or a top-range magic weapon (+5 vorpal sword), for instance.
I use Market Price for magic items not as a catalogue price, but more the way Neverwinter Nights does - as a rough mid-point between the easy-sell price (50%) and the easy-buy price (200-400%). Market price reflects the actual difficulty of making an item and is what the selling & buying prices gravitate towards. In a notional perfect economy with 100% availability of all items, everything would be bought & sold at the market price.
As it is, adventurers selling loot get at least 1/2 market price, but can use Gather Information to get closer to the market price. Buying, they pay at most 400% market price but can use gather information, friendly contacts, diplomacy etc to get magic for closer to the market price.
Professional merchants - including wizards making items for sale - get at least market price. A wizard making goods for a Duke will receive market price from his liege. But he can use gather info & other skills to get more, up to around x4, or whatever people will pay.
Some common magic items have actual market competition and can be bought for closer to market price, eg cure potions. Very rare items or needed spells may cost much more than even x4 base to acquire - a resurrection spell or a top-range magic weapon (+5 vorpal sword), for instance.