unfortunately no... despite like 8 pushes i made in cc to make them sellable. I think the mentality is they dont want people playing realtor with gangsheds, especially since, even though you can't use them, you can still own then with inactive gangs. I see the other side of this.
Someone's looking at about 50 mil to buy it and then upgrade it. Plus whatever you'd be expecting them to give you for you to sell it to a bank.