Used Rohn AX tower, 40 ft = $125
Paint = ~$80
Bolts, nuts, etc = ~$20
Homemade ginpole = ~$10 (10 ft pipe with pulley welded on, cheap rope)
Hole = Free, shovels are great.
Concrete = ~$150 u-cart.
Grounding = ~$50
As said, you don't need a yagi on top at first. Just use it as a dipole...