Sades,
I'm pretty sure I've read that you can get a free upgrade if you bought stuff in the past 30 days. Ask one of the mods, they'll be able to confirm this.
[Update] I've found the other forum here: showthread.php?t=16743 - it mentions a free upgrade if you've purchased Super Suite in the previous 30 days, but if you bought several extensions you never know, they may give you the same offer.