Protective plastic bag for shipping electronics

I'm in the process of selling off one of my integrated amps (it measures about 19" x 15" x 5") and though I have the original double box, I don't have the protective plastic bag that would have originally come with it, and I don't want to ship the amp without it. I've looked around pretty extensively on the internet to find a source for one of these bags (probably 3 or 4 mil thick) but no luck so far. Manufacturers must get them from SOMEWHERE. Does anybody know of a source? Thanks!
Just use a couple of kitchen trash bags. 
FYI: has anything you want for shipping.
I use Glad-Cling Wrap, which is a stretchy kitchen wrap. I completely wrap the component, on all sided, in a cocoon of multiple layers of the wrap. It works brilliantly. It provides a very tight wrap that cannot move and will not allow any abrasions to the component. I've used it many times and always receive excellent buyer feedback regarding my packaging/shipping.  
There is a product called "press and seal" by Glad, which actually seals air tight. It is not clear like cling so you might want to go with the cling for aesthetic reasons.  Otherwise it is remarkable stuff, I use it now for all my plastic wrap needs.

I have press and seal in my kitchen also. However, for delicates (I consider my audio gear delecates) the soft, stretchy Glad Cling wrap is the ticket....