Hi buddha01,
as far as I know the TMI don't sell this. If you go to Lifeline, you get a cd with F21-F27 sounds for taking home. There is a HemiSync cd I own called "Transcendence" which feels like going very high partly, but it's not the same as a F27 tape. Also, one piece of "Mystic Realms" felt like taking me above F23. But I don't know how others respond to it.
Maybe someone else sells tapes of that sort, don't know, or you find out the right frequencies and make your own one (every normal computer is a potential audio studio!).

Back from Gateway Voyage I listened to F21 sounds, and was able without a "higher" tape to go to the other Focus Levels. Once I had a place in F21 I could easily visit, I asked for little trip beyond F21 to see the Monroe Rings. I then jumped into it and did my first retrieval. What happened was like the method Bruce tells about. I used F21 as a base, and then asked, and I felt there were helpers behind me who were guiding me, if not carrying me like they were my wings. So, if you can reach F21, check out if you can go beyond it. The F21 HemiSync sounds in my experience don't hinder you to go to higher Focus Levels.

Spooky

PS yes, "Surf" is also a nice tape...(but not especially for above F21. Although, I use to say in F10 everything is possible, look for helpers, they can make a Silver Surfer out of you...)