I agree with both of the above.
I would also include in the spreadsheet, the "cost of ownership" in monthly breakdowns. Include loss interest on the purchase cost, insurance, etc.
Right now, you are looking at being able to sell at a fairly specific price right after you no longer need it. But, as mentioned, you may have to wait a good while to get that price or sell it for much less to get rid of it quickly. Knowing how much it will cost you each month while trying to sell it will help identify your breaking point (minimum sale price and longest time frame before your investment is a bust).