Bet that set you back a bit!
So something like this:
Black Steel Square Plate 150mm x 150mm x 10mm Fixing-Mounting - Mild Steel
http://www.ebay.co.uk/itm/290970833950
10mm Mild Steel Disc 200mm Diameter
http://www.ebay.co.uk/itm/320928337266
Black Steel Square Plate 300mm x 300mm x 10mm - Fixing-Mounting -Mild Steel
http://www.ebay.co.uk/itm/290997481550
So something like this:
Black Steel Square Plate 150mm x 150mm x 10mm Fixing-Mounting - Mild Steel
http://www.ebay.co.uk/itm/290970833950
10mm Mild Steel Disc 200mm Diameter
http://www.ebay.co.uk/itm/320928337266
Black Steel Square Plate 300mm x 300mm x 10mm - Fixing-Mounting -Mild Steel
http://www.ebay.co.uk/itm/290997481550