I build these basically with leftovers from our new fence. The coffee table is 4x4 post legs with a 2x4 frame attached underneath. For stability, I used a 12" wide scrap of 3/4" plywood on the top before attaching fence pickets. Old tags were used on both sides and ends. The (two) end tables were 2x4 legs with 1x4 side trim pieces, but without the plywood stabilizer, and a single cut down picket for the top.
Estimated Cost
A guess here, since it was all leftover lumber, but I'd say about $20-25 for the table and $6 for each table.
Estimated Time Investment
Afternoon Project (3-6 Hours)
Recommended Skill Level
Beginner