I don't know about the TJ, but when I had an 07 JK w/soft top I had it priced out at around $2,400 through the dealer. You'll need a wiring harness for the wiper/defroster and a new turn signal stalk if you want stock switches. And the doors, of course.
As it's much easier to go to a soft top from a hard top, this time around I bought it with the hard top and added a (yet to be delivered) Bestop soft top.
You may be able to find a hard top for sale by someone, but I think you'd still need to get the wiring harness. Someone may know of a DIY workaround, though. Good luck!