There is still much interest in high quality (TDK/MAXELL/SONY) cassette tapes from mainly the 1979 - 1992 or 1993 era among a very loyal ANALog group known as TapeheadsDOTNET.
http://www.tapeheads.net/index.php Most of us, overlook that still anybody these days is using DAT or Cassette, but there is a strong loyal Cassette following. It has gotten even stronger in their desire to find useable quality Cassette/Reel-To-reel/useable DATs for those that use them.
Perhaps, many of you are not aware that the MAJOR brands, no longer produce anything on cassette that is Quality tape anymore.
Only Sony HF normal tape, TDK D, normal and a TDK SA tape which is the only TypeII tape around these days, and it's no longer TDK's design or old SA formulation. Metal tape has been gone for almost 10 years. The last era of XLII Maxell cassettes were no match for the pre 1995 tapes.
So, what else is left in Cassette tape for ANALog tape lovers, well about the best tape in existence is National Audio Company (in Missouri) has quality type II high bias 747COBALT tapes & 751CHROMEtapes which are sold unlabeled/unboxed/without cases or J-cards. It is the best new tape around in 2011.
There is huge demand for ancient NOS TDK/Maxell/SONY cassettes from circa 1980's. Seen what ebay prices have been for Metal tapes and even Tdk SA-X and TDk-AD from the eighties era?
USED Tape is desirable, these days, as there is no other option for quality TDK/Maxell/Sony cassette formulations.
Don't just toss out your cassettes. People are hunting those tapes at thrift stores and flea-bay.
I know it sounds crazy.
Check the postings at TapeheadsDOTNET if you don't believe it.
Used Metal & top quality used TDK & Maxell type II tapes and any type III cassettes are in demand these days.
The same holds true for Quality used Open Reel Tapes.