Got mine from a friend who has a small steel business. £100 for two - absolute bargin.
Think you need to look up 'Steel stockholders' in yellow pages. I tried looking on the internet at the time ('cos I new he was underchanging me and I wanted to pay him the real cost) but couldn't find a supplier on the internet.
Size of mine were 205mm x 135mm. I needed 5 or 6 people to lift each one in place, so you might need eight people. If it's just for a garage you might be able to find something smaller and lighter.
Make sure they supply it 'red' - ie painted with oxide.
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