Howard my sugestion is to buy The Land newspaper and check out the shed adds on the bottom of the pages, this way you can get an idea of standard size prices. I would start with a 3 bay with 3 sides clad and 1 bay inclosed. If finances are tight you only need to concrete the inclosed bay to start with and you have a comfortable work area. If you later need more bays you only need to take the end cladding off add a couple of bays with back cladding and put the end cladding back on. Inclosing more bays is as simple as moveing the internal wall and purchasing more doors. It helps to have a BBQ shed raising party also but keep the workers sober enough to read the plans. My 2 bobs worth.