Except for some trim work and paint, this is essentially done.
So...what would this cost you to build.
I have $65 in the cattle panels, $25 in 2x4s and $40 in concrete pavers.
The 4x4 beams would be at least $12 each and you need four...$48.
2x4x96" studs for framing & floor joists @ $3 each you need at least 20 and probably 24 .... $72.
Two 4x8 sheets of OSB for the floor... $48.
Three smart side 4x8 sheets of siding for the front and back... $80.
$25 for the window.
$45 screws, nails, hinges, joist hangers and lock mechanisms.
$35 for the tarp.
$475 give or take, estimated from the last time I bought this stuff.