as far as i know, Grant, when you get an LEdition, you can purchase an upgrade to the full edition, of that version number. then, you'd have to purchase the upgrade to the newest edition. i'm not positive of that, but that's how i think it works.
if you're pressed for cash, try buying through a student discount site. if you're not in school, enrolling in a photoshop class at a local community college, is usually enough to qualify for the discount.