I would figure about $100 a night including taxes. You would definitely be able to find some less than that, but I would use that number for budgeting.
As an example, we are staying at Bonnet Creek in a 2 bedroom over President's Week for about $100 a night with tax.
In years past we have stayed at other condo resorts like Cypress Pointe, Silver Lake, Orange Lake and Regal Palms and have paid about $80-100 a night with tax.
Hope this helps you out!