Indeed. Star Wars is basically a cash machine for Fox, Disney will likely have to pay through the nose to get the rights, and that's if Fox would even consider selling it, which is nigh-on impossible. The potential profits down the line with Disney releasing new Star Wars movies is insane for...
There are digital versions of Star Wars I-VI... including IV (which Fox owns and will not give up to Disney so DMA is not available). You can buy Star Wars I-VI on iTunes, but it is unnecessarily expensive at $100 for the (6) movies!