Do you need a downpayment for a mobile home?

We currently own a commercial property with a shop (my husband uses for his business) and two apartments. We use one apartment we rent the second for $650.00 mth. We would like to purchase a mobile home because they are inexpensive but we are getting to old to go up and down the stairs of the apartment. We do not have the downpayment. The mortgage is with a personal company and is interest only payments, we will never pay it off, but plan to sell it, although we anticipate it will take a long time to sell because of location and economy.