Once you have decided on a studio, an engineer, and a producer, it boils down to money. You need to ask some very important questions to get the most for your money and negotiate a better price. (This information can also help the studio owner understand how to prevent any miscommunications with his clients.)
If you are like most people, you are working within some kind of a budget. You need to get as much information as you can from a prospective studio so you can negotiate the best price, and so there will be no financial surprises when you get the bill.