What my father used when I was growing up and I still use is just take a Mason jar, poke some holes in the lid with a nail. Place a piece of panty hose over the jar then screw the lid back on.
I know this is a bit late but for anyone out there looking for washer/bolts, I have ordered from these folks before for several projects including my chicken abode. They ship quick and most washers are less than 5 cents. Their shipping is also dirt cheap. http://www.wholesalebolts.com/
If someone charged your friend 300 bucks for that then shame on them.... sounds like there are more than one type of predator outside the chicken coop. Put you some wheels on the back and it you will have a good moveable coop. You can start with what you have and do a few modifications and it...