Reli said:
Was this from a store of some kind? Seems odd that anyone would bother selling anything for 10 cents.
Also how do you know what kind of equipment they were recorded on?
St. Vincent De Paul is where I got them. They sell pre-recorded (store bought) used cassettes for $.50 apiece. Blank cassettes that have been recorded by the customer sell for $.10 apiece. We were out "popping tags."
As far as the equipment that they were recorded with, I used my M-90 and my ears to judge that. Maybe "high quality" is a product of my excitement at the find, and "good equipment" would be more discerning. The levels are perfect. I do know that on some of them you can hear the slight crackle of needle on record album right before each side. Those are the TDK SA's, of which there are three different generations of. From comparing them to my collection, I date those tapes from about late 80's-early 90's.
The handwriting on the cassettes, all of them, is the same. Delta & Chicago blues, Beatles, Heart, INXS, Madonna, It's like someone was making me a B-day present of an assortment of 20th century music.
Full of great albums recorded at perfect levels with high quality equipment. 
