when you place an order for a product you can choose a type of buying strategy called fixed price. but when i place an order for lets say a fixed price of $500 it tells me that it will buy it for the market price. which is not what i want
I'm reckoning that you're quite new in which case best price is your only option. I dont think this is a premium member thing, just a matter of how long you've been playing.
I'm not 100% on this topic so I hope someone else can clarify this for us.