I know of a site where you can get the following:

500 - 4 x 8 Bubble Mailers for $53.67.

That comes out to about .9 cents a peice.

Here is the site:

http://www.papermart.com/mailers_welcome.htm

I am not affiliated with this site. I have just purchased stuff from them many times and I haven't found anyone that can beat their prices.

500 bags is alot but you could always break it down and split with another member.

Keith