Here ya go bro,
http://www.shelterlogic.com/sheds-and-storage/small/
http://www.campingworld.com/shopping...ox-8-x-8/48653
You could get some 6 mil plastic put that down on the dirt and lay skids down and screw some 3/4" pressure treated plywood down to the skids.
Well below your $600!, I've been kicking one of these around for a few years now--I have a decent shop but always looking for a little extra space. I'm over built on my 3/4 acre. I think Northern Tool also sell the Shelter logic Brand. Google may even turn it a bit cheaper. I know we have Pep Boys around me (like a Schucks of Kragen) and they have a 12 X 20 Shed/Garage similar to the Shelter logic stuff for $208. Also you can look @ Sams club, Costco and Bj's, I've seen them there too. I know it may be lame looking but you can also put other stuff in there, you don't want to WD-40 your lawn tool handles
Just a cheap idea
1985 Honda 125M (My first Trike--Still have it)
1986 Honda 250SX
1981 Honda 110
1982 Honda 110
1986 Yamaha YFM80 (Sons quad)
Past rides: 1983, 1984 200X, 3--1985 Kawasaki T-3
1987 CR-80, 70's vintage XR75, RM 370