Ratling traders don't sell if asked for more goods than they have
If the player asks to buy ratling traders more items than they have, they will tell they only have x amount, but will not sell them.
If a ratling trader has 50 cooked lizards in stock and the player asks for 51, the trader will tell he only has 50 in stock, but he will not sell them. The player needs to ask again for the exact maximum or less to buy any.