You'd have to be a fool to order that from Apple. Their upgrade prices on SSD's are a joke! It'd probably be cheaper to wait it out a couple of months and get an external thunderbolt one - it'll be just as fast if not faster!
Or I don't have the time to do it myself. And have no experience taking apart computers so I'd rather not risk removing the glass and doing serious damage. I will gladly upgrade RAM on my own, but not the hard drives.
The SSD + HD combo (with OS X pre-installed on the SSD drive) is a great combo for me and worthe the price. It's the wait that's going to be torture.