Well, over here in the Great White North, a sheet of 3/4" plywood costs about 60 bucks, and 1/2 inch is about the same depending on quality. You will need about 6 sheets of each, timber for the base, different sizes of screws, glue, paint, primer, etc. etc. etc.
I haven't been keeping track, but I would estimate that I have put about $1000 CDN into my box so far. And I haven't found glass for the windows yet.