Can you upgrade from Logic Express 9 to Logic Pro X?
Can you purchase an upgrade from LE9 to LPX instead of paying full price for LPX?
Mac Pro, OS X Mountain Lion (10.8.3), 8 CORE/24GB RAM/4TB HD/Dual Monitor
The Mac App Store doesn't offer an upgrade price. It's the same for everybody. Anyway, Logic Pro X is much cheaper than Logic Pro X in the past.
You have to purchase Logic Pro X for $199.99 in the Mac App Store. You will keep the Logic Express version you are running now in case you want to delete Logic Pro X