I think consideration needs to be given to tomh's approach. Sounds like you've got over $50,000.00 in work and maybe twice that. You could get a contractor in there to give you bids. This will help identify what needs to be done in addition to cost.
It's math. What will this house and are surrounding houses worth less what you pay. Can it be fixed up for the difference? A home inspector may also be a source of information.