Clients always ask me at the beginning of their projects "how much will this renovation cost?" A totally reasonable question. When I go to a store, I want to know the price of a product as well as what it looks like and how it works.
Obviously, the cost of construction is one of the critical components in a deciding if a property is worth the purchase price.
Less obvious to you, my clients, is that the cost of a renovation can vary wildly because every existing building is different. While general construction square foot costs can be useful, they have little accuracy in renovations.
Without a drawing, or at least written document, to help start the conversation, the best we can do is guess based upon past experience.
My suggestion? Hire an architect (or do it yourself) to spend eight or 12 hours visiting the site, discussing the requirements of the job and sketching a scenario that can be priced by a friendly contractor who will provide budget numbers at no cost.
The 1,000 dollars you put out upfront will be well spent towards providing you with peace of mind. If you buy the property, the work can be used in the development of the project. If you don't buy the property because you found out you wouldn't be able to afford to fix up the property, the money was well spent.