Amazon only has a couple resellers that look to have no direct connection to the film and are selling way higher than msrp.
Might I instead recommend buying direct from dirtroadtopsych(dot)com, or from one one of the wonderful local happy-mutant-friendly independent record shops that carry it? Direct purchase from official site is only $23/$26 (US/INTL), shipped.
"Also available at Waterloo Records, Antone’s Records, End of an Ear Records, Wild About Music, Oat Willies in Austin. Jackpot Records in Portland, OR and GetHip Records in Pittsburg, PA." (http://dirtroadtopsych.com/purchase-the-dvd/)
PS: [No affiliation, just a fan] AustinPsychFest is totally worth checking out, or checking out again if you gave it up after one of the very crowded smaller venue and alley years. The line-ups are phenomenal, the new venue & stages are excellent, the tickets are affordable, and there is on site weekend camping. Bonus: 3 days, 0 minutes in restroom lines - there were that many port-a-pottys, and they were clean and not at all...full. I think PsychFest had more of them on site than ACL did last year ;!).