Depends how nice you want it,but say engine box suspension ,bushes brakes etc,new panels welding ,descent repaint inside and out is going to be 5k plus then interior and all the jiggly bits I think your gonna be over 20k if done nice,that’s not including your time,
As many will tell you,we spend more on them than what they are worth but you get so satisfied seeing the progress,unfortunately a lot never finish them as the years soon go by,If it’s something you can do a lot of the work on then make them an offer,if you’ve got to send it out for others to repair don’t bother as you could probably buy a nice 3dr for what it will cost
ps,as others have said be far cheaper getting a nice early 3dr mk3 to start with