I was thinkin the same thing, all i know about junk items, are that they are normally not able to be sold in the ge, so they just sit either in ge trying to sell or in your bank. Sorry i can be of no other assistance.
Junk is made by fletching. I.e. Willow Longbows (U). ect. You don't buy the junk (usually). Or you could buy the junk at .25/m then loan your ags out for 2m/24 hrs and then you make 50c a day doing nothing.
Junk is stuff that cannot be actively sold on GE (since everyone is trying to get rid of it, and nobody wants to buy it). So generally, it has no actual value even though it has a trade-price value.