Cheap solution to vertical bicycle stand I would like to know if there is a cheap way to put up my bikes vertically on a wall (like a hanger that I could put my bikes' wheels on).

I am doing this because firstly they are taking to much space just being parked there... Secondly I have heard people say that the tire gets destroyed if the bike is left for a little while unattended, which is the case.  I have three bikes that I use. The one is used every third day or so, the second one once in two weeks and the third one, almost never...

How do you suggest I build this vertical stand for three bikes for under $20? I have googled this to see if someone has found a way but I only saw some really complex stands and hangers, as well as expensive products.
Free wood from pallets could easily be fashioned into racks that can be fastened to the wall with butterfly bolts.  Also, consider looking for solutions at http://www.bikehacks.com/