For example, if a property record costs 200 DOOR. And the current price of DOOR is $.01 USD. Then you are paying $2 per property. If the price of DOOR goes to $.10 USD, then you are paying $20 per property (assuming you need to buy more DOOR Tokens to continue to buy Property Data.). Therefore, it would make sense to purchase enough DOOR to pay for Property Data made available in the foreseeable future. Having a healthy balance of DOOR in your account will avoid inflation of cost per lead.