I have an original and still sealed Johnny Crash "Neighbourhood Threat" case the that is still sealed. The cassette number is NT 45126. I cannot find it anywhere.
A new one on Amazon is $28.99. Used ones go for as little as $3.47.
It looks like the CD and maybe LP may be worth a little but the cassette price (new or used) seems to fluctuate a lot but never for very much money (sold that is).
Here is a link to the sold items on eBay - covers several weeks of sales.