I wanted to make a black and brown picnic table, this one turned out really nice and it gets a lot of compliments.
I, also, reinforced the 2x6s used for the seats by boxing in 2x4s underneath. I just cut 4 53" (probably could have been 54" honestly) and mounted them to the bottom of the seats and screwed them into the seat cross members. This should keep them from flexing.
9 2x4 - 8' - $30,
Screws - $25 (headlok and kreg),
8 cans of paint - $35,
(already had sand paper),
8x valspar color radiance paint + primer Dark Gloss Toast (1 coat)
I will probably also put a clear coat on it to help protect it some