Face, my math works out pretty much the same or less, (except for the farrier) except when I consider property tax, the cost of the tractor, fertilizer, lime, diesel fuel for the tractor, the hay shed we put up, etc. - all the things that allow us to maintain our place decently and keep the horse care cost low.
Now, I am not arguing that home care is not substainally cheaper than boarding, it is. The only board I could afford after having children and before have our own place was self care pasture board.
However, I have seen a lot of people get in to keeping a horse at home and do it very badly because they didn't realize the actual costs, equipment or work involved, and I want to make sure that the OP has the total picture.