Money received on the sale of collectables is just reported as other income. There are no deductions for that, other than what you actually paid for the item. Additionally, losses on such a sale are not deductible either, since losses on personal property have never been deductible.
I'd treat it like the other SCH C business property myself. But I'd not be claiming years worth of storage fees, as I would fully expect such a claim to set off fire alarms at the IRS, which would be the same as hanging out a sign that reads, "HEY! IRS! AUDIT ME NOW! PLEASE! HURRY! QUICK! FAST!"
When it comes to business inventory, nobody in their right mind is going to pay money to store it for years. Inventory is expected to move, and move rapidly, generally. Even car dealerships that deal will millions of dollars of inventory, can generally move it all within a year - even if they have to sell at a loss to make room for something they can sell for a profit.
