If you purchase ClassiPress now, all future upgrades are free. There hasn't been a confirmation of any sort function in the next release though, so if you're expecting this feature specifically you may wish to wait for an official announcement of features on the
AppThemes blog prior to purchase. If you're planning to customize the theme yourself to get the sort function then this is entirely up to you.
ClassiPress is not encrypted, allowing you to customize it freely. You will get the full source code with purchase of any licence package, although if you're also wanting the PSD files you'll need to purchase either the Professional or Ultimate Edition licence.
