Find yourself a lumber yard with a "cull" pile. They'll either give or sell you (cheap, cheap, cheap) their discarded cedar fence pickets. You're handy with a circular saw (I know this...). Use it to trim off the damaged portions of the pickets (which is why they can't be sold).
Simply construct a small "pallet". Space some 2xs across as feet, and either nail or screw (I use outdoor Deckmates) your sections of cedar fence pickets to the 2xs.
I constructed one of these to lay across some uneven yard space for three raised planters. It has lasted approximately 2 years. Would've lasted longer if I had used only one more 2x. The weight of the planters wasn't supported well where that 2x was missing.
All in all, I'll be making more of these for my patio planters. They look great, too!