It really helps to hand pick your own leather, but not always possible. That is when you have to rely on some dude in a warehouse, who doesn't know you, or really care.
It sounds like you might be new to leatherwork, and if that is the case, don't spend the extra for top shelf that might be B or C grade at grade A prices. Find a place close by, try them out. When you hone your skill, and find a good supplier, then you can spend the extra.