Okay, so the rules don't specify how buying works on page 150 CRB... So the first thing I assume is that the positions are simply reversed. Selling works completely the same for either an NPC or a PC. If a PC wants to buy something, the NPC simply follows the selling rules as described on p150, except now that it's in reverse, it seems broken.
So here's my flawed assumption in action:
-Lando wants to legally buy a Personal Deflector Shield which costs 10k.
-He makes a negotiation check to find it on Coruscant, so he's in luck today and manages to find it with no cost increase due to rarity, as described in Table 5-3.
-Now he wants to actually purchase it and this requires a second haggle roll.
-A personal deflector shield on Coruscant has a rarity of 6, making it a hard difficulty check.
The NPC now sells the item, using his negotiation check against Hard.
Note that Lando has no haggle check. The NPC is checking against a difficulty table.
Because the check is so difficult, the NPC has 1 net hit, so the personal deflector shield is sold at one quarter of the list price, at only 2500.
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I think I've got this all wrong. P114 describes "Extra hit on a negotiation check may be used to increase the acting character's profit by 5% per hit."
So I made a bartering flowchart.
Step 1: Find the item's listed rarity in the book. The GM adds rarity modifiers due to where the item is being sold or purchased. Determine the difficulty of the rarity check in Table 5-1.
Step 2: PC attempts to locate the item or where to sell the item, legally with Negotiate, or Illegally with Streetwise, or any other skill allowed by the GM.
Step 3: If the player is purchasing the item, go to 4A. Sales go to 4B.
Step 4A: The PC has found the item and rarity no longer affects the purchase. The PC and NPC make an opposed negotiation check, and every success the PC gets nets him a 5% cumulative discount from the base cost. Purchase finished.
Step 4B: Go through the process on Table 5-3 (determine rarity increase difference, multiply the base cost of the item, determine the final sale value, which is a percentage of that multiplied base cost, with a negotiation/streetwise check). Sale finished.
Can someone help me revise my bartering flowchart, as to how FFG intended it to proceed?