How should I go about finding any prerecorded s-vhs tapes? I can find the small list of titles ever offered in super vhs but I can't find a picture how the markings/packaging differs from regular vhs releases.

i think the most you'll ever find beyond a tiny handful of demo tapes are a relative handful of Film and Anime releases intended for Japanese domestic market.

by and large, S-VHS failed to appeal much beyond the Prosumer and Industrial Editing/Dubbing markets...

Blade Runner
Canyon Dreams
City Slickers
Misery
The Terminator
Days of Thunder (LBX)
Ghost
Godfather Part III
Star Trek II (LBX)
The Voyager Odyssey
Hunt For Red October
Star Trek VI
Indiana Jones and The Last Crusade (LBX)
Star Trek IV
Top Gun
On Golden Pond
Superman
Nature's Symphony
Nature's Serenade
The Worlds Below
Desert Vision
Water Colors
The Worlds Below
Elton John
On Golden Pond
Sophisticated Ladies
The Emerald Forest
Scanners
White Mischief
The Rolling Stones
Jazz in America
The Last Emperor
A Chorus Line
The Princess Bride
Robocop
The Nutcracker
When Harry Met Sally

This is the unconfirmed list for the US releases. I don't have any pictures, no idea how to spot them.

I was alerted to an ebay auction for The Terminator on S-VHS right here on the board on this thread . . .

Are there commercial movies on Super VHS?

. . . and I have found other S-VHS pre-records on Ebay (searching for S-VHS in the VHS movie section and sifting through a lot of non S-VHS titles where the title ended in "S" right before the term "VHS.") They don't show up very often and when they do, a lot of the times the seller knows he/she has something rare and gouges for it (like that S-VHS copy of Indiana Jones and the Last Crusade that went for US$60.)

They turn up so rarely that I just stopped looking.