Are you a new player?
Read the documentation. The question would have been answered.
We need a new forum style. The kind that allows for stickies at the top of the list of threads for new players that reads, "At least read the documentation before posting a question to the forum. Odds are, the answer you seek is contained within. Also if that does not help, search the help threads for a similar post or question. You may find your question already answered that way as well."
I used to think that forums I read that posted that were pretty ignorant, maybe even rude, but it is posted for a good reason. People tire of answering the same question over and over.
The likely short answer is that you are not a full member. Non full members always use "best price" I think that is what it reads.
I too am guilty of not reading the documentation for months after first playing. So I am not trying to be mean. I just want to help you understand why some folks may not be answering this question.