Hardware and Fasteners - Variable height storage shelf

I have a couple of items I use occasionally, each of which weighs about 25-30lb (a computer monitor I only use for testing, and a compound mitre saw). I'd like to put them on a shelf in my garage, that I can raise with a ratchet, crank, pulley or some other such mechanism, so they are up and out of the way of the cars, but easily accessible when I need to use them. I've tried googling on variable height shelves, adjustable height storage etc, but can't find anything other than industrial jacking equipment that cost several hundreds of dollars.
Any ideas?

Ran across this. Maybe not as sophisticated as what you wanted, but wow at the space it will create. http://www.houstongaragestorage.com/installation.html

I have plenty of storage space in my attic, but it's not convenient. I've already missed my footing while descending the folding attic steps, and spent 3 months in rehab. I certainly don't want to have to haul the stepladder out of the shed, and try getting down the ladder while holding a monitor in both hands.
I just need to be able to raise and lower a sturdy shelf three or four feet. This doesn't seem like rocket science - every stationary power tool I've owned has a crank to raise and lower either the head or the work platform.

Here's a crank I use to hoist bikes in the garage.
http://www.geocities.com/oneofamill/pics/100_3236s.jpg
http://www.geocities.com/oneofamill/pics/100_3238s.jpg