an SSD to me is more than just bigger numbers. it transforms the user experience and removes a ton of aggravation from waiting on your computer (I'm impatient in front of a keyboard). that said, any upgrade you buy from apple is at an rip-off price so just evaluate what's more important to you. personally i'm ok with being ripped off a bit for an SSD because they are just so awesome, but not for RAM beyond 8 GB.
Good point.