Odd. Looks like you are right.
Gas-s-s (not sure how many S's) is directed by Roger Corman and since it is a double-feature disc, I searched that way.
I did find the Psych-Out/The Trip dvd there. Richard Pryor is in Wild In The Streets and I didn't find it listed that way either.
You should find the disc at Fry's or Best Buy for $10. I think there are better supplements on the Psych-Out/Trip disc (commentaries, documentary interviews...).
The MGM double-features series of AIP films is a good deal.
Netflix has a stunning amount of DVDs, but every now and then I can't find what I want, damn it. I keep wanting some BBC shows (Dave Allen etc) but I guess they were never released on DVD.
Regardless, I think Netflix is one of the top 5 businesses on the net.