Hey @Nebdar
I am not completely sure, but I think it is 25% for both.
But on lot's of traders in the game there is no diference in the price between f2p, preferred and sub.
Hmm someone checked in game and....
To muddy the waters a bit more:
I took a look at Felusa Stato's inventory with all 3 types of accounts and always got the same prices, for example 2500 Credits to buy "Arangement: Basic Lounge" and 100 Credits for selling it back despite the warning about increased prices at the bottom of her inventory.
Then I went to the Republic Fleet and took a look at V1C-ORY (Conquest Reward Vendor) and Luna (Companion Gifts Vedor), they also showed the same Prices for F2P and Subscribed accounts.
Finally I went to Baric (Speeder Vendor), here at last I found the Prices for my F2P and prefered Accouts to be 25% higher than for my subscribed one.
So it seems that the prices are not generally 25% higher but on a per Vendor basis
