Magic item sales and availiability rules.

Availiablity:
skill - Gather information DC 15 for gp value of 1000 or less.
+2 synergy for bardic lore
Base DC:
Total value of the shop:							DC
1000										15
2000										17
4000										19
8000										21
16000										23
32000										25
64000										27
125000										29
250000										31
500000										33
1000000										35
+1000000									+1DC



Only 25% of the value is on the highest powered item possible.
So a DC 23 16000 gp shop could only have a 4k item max.
To locate a specific item: +10 to DC. 
So if you wanted to find a 2mil item, the DC would be to find a
8000000 gp shop that has it. DC 52.

Price:
skill - Bluff (or Diplomacy -5)
If both, then +2 synergy.
Base market value = Shopkeeper's Bluff Score (assumed to roll a 10 if not opposed).
Shopkeeper Bluff Value : 10  +1 per 1mil of shop value 
Modifiers: +2 Planar Trade consotorium, +5 Merkhant, Sigil +5, Union +5

+5% to cost per point below 20.
-1% to cost per point above 20. Max cost reduction 50% (DC 70)
Sell back is 20% + 1% per point.
Sell back price is max 50% (DC 30)
Can be increased by setting up a market and relying on other's rolls.