HELP PLEASE

Fujimi has produced a few kits of tools and people just for a garage scene. They also produced a two-sided garage diorama that may give you what you need. I'm not sure if Fujimi is still producing these, so a quick search might be in order if your local hobby shop can't be of help.
You can also think about photographing posters, magazines, oil cans/cartons, garage type products,.........etc. After photographing these items, size them and print to use on your own computer. If you don't have an art program, or a computer, you can have photos printed and just use them.
Good luck!

Here are a few links that might give an idea or 2.
http://website.lineone.net/~declan.oreilly/index.htm
http://www.geocities.com/PicketFence/2090/model.html

I forgot that I had this one also http://www.scalemodelingbychris.com/page_two.htm

Chris posted some good links I have bought one of the Garage kits from Scalemodels by Chris.

Heres another one I think you will like. Guys is out of Bradenton Fl and I have ordered from him more than once, has just about anything and everything you might or might not want for a dio scene including a Cheeseburger! ROFL

http://www.seltd.net/index.html
Scale Equipment Ltd! Good Stuff

Gmpdiecast has a few garage accessory sets also. they include all kinds of kool parts such as tool box's, creepers, jacks,and jack stands. it also incudes an air compressor.
wal-mart also has a nascar detail set which includes a cherry picker, tool box, and a few other pieces including an engine to hang from the cherry picker. i have been gathering parts and bits for a garage/shop dio for a few years now, and my wife has double dog dared me to actualy build it. so as soon as she triple dog dares me, out comes the plywood and everything else to start on this new project. good luck on your project and post some pics along the way, I TRIPLE DOG DARE YA!!!