App Store only sells latest OS X version? Can't get Lion 10.7 anymore?
It is still possible to purchase 10.7 for installing/upgrading on your mac, see my answer at question Can we still upgrade to OS X 10.7 now that 10.8 is out?:


  Although you can no longer buy Lion through the App Store or directly
  by SKU from the online store, you can still order Lion after Mountain
  Lion was released.
  
  I called 1-800-MY-APPLE, it took some time to get through but they
  told me that I would be able to purchase Lion, OSX 10.7 from them for
  $19.99.  They would send me the physical copy through the mail.
  
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