Invitation from Mountain Lion

I've got a mail from Apple store to promote downloading the new release update OSX10 version8 called 'Mountain Lion' for $20.
Actually I'm embarrassed to purchase a new version so early since I had downloaded 'Lion' the former version for $30 only a year before.
I've not used it better than ever because I'm totally satisfied with iOS5 in my iPhone4.
I've not often used Mac book better than before because of iCloud.
I can search on Internet or post blogs all from my iOS. It's no use for me to pay for the new OSX.
And it makes me feel uncomfortable that Snow leopard users can only pay for $20 to get Mountain Lion as the same as Lion users.
What was $30 for Lion users like me?
I think it's unfair for me to have paid for Lion should pay the same $20 as the ones who don't have Lion to download the new version.
That's why I'm not going to buy Mountain Lion.