You have to become an Advanced Reviewer. That doesn't just happen. You have to work your way there. I see that you have not written any reviews so I can not even begin to judge your writing ability. However, I am going to assume that you are new to all this and don't have much knowledge about the information that should be included in a good review. Therefore, I would suggest you take part in the Mentor Program. You can find information on it here: link
To find the list of available mentors, click on Community Corner and scroll down. You'll find the list of mentors near the very bottom of the page.
If you go through the Mentor Program, you'll learn how to write good reviews and when you graduate, you'll become an Advanced Reviewer. After that, the price of the items you'll be able to request are determined by your ranking. Therefore, the better your reviews and the more effort you put into them, the better the items you'll be able to receive.