Having experience with steel, wood frame, and pole buildings, steel buildings are the most expensive and wood pole buildings is the cheapest. I went the other route and did a wood frame which is probably the best bet if you want it finished inside (plumbing, electrical, insulation, sheetrock). Mine is 30x50 with apartment above 30x30 and 12' ceilings in the remaining 30x20. It cost around $100k but that includes the finished apartment and everything. My dad put up his 30x40 pole building for around $6k, just the shell and its unfinished inside. The 40x60 steel building I put up a couple months ago was so ridiculously expensive I don't know why anyone would go that route, and I could carry on about all the other disadvantages of this type of structure but the cost should make the decision for you.
