Michael, what does the price at which a used piece of equipment have to do with anything? Many of us -- look for threads here and elsewhere on "your best snag ever" -- have bought used gear at prices far below current (or even contemporary with the purchase) market price. Every once in a while there's a pricing anomaly ...

I don't think that the OP's lens was seen as a piece of cheap trash when new. Convertible lenses were serious ...

Did I ever tell you about the time I bought ten (10) 38/4.5 Biogons for $580 delivered?

Oh, and by the way, I salute the OP, who hasn't always had two dimes to rub together, for hazarding $30 on a possibly crappy unknown old lens that cleaned up nicely and turned out to be very much to her liking. Been there, done that, am probably the better for it.