$6?? Are you talking about those short 6' landscaping timbers? We use those for flower rails... but the average pole for a jump is 12feet long and I have NEVER seen them for even double that! We buy our jumps from shows. The poles are about $20 but they are primed, painted, and extra heavy duty.
Quality wood poles are expensive and heavy but I prefer them HANDS DOWN to PVC. I can't stand PVC for all the reasons people already stated. We use PVC wing standards with wood inserts in the feet so they don't fall down (and I've seen THEM shatter!) with wood poles. Best combo IMO.