Starrett makes a 12" extension for hole saws.
Product number ( these are canadian part number, I don't think US uses different ) :
A5 : Extension for 1/2" chuck. Will hold A2 Arbor ( 1 1/4" + sizes Holesaw )
A15 : Extension for 3/8" chuck. will hold A1 Arbor ( 9/16" to 1 3/16" sizes holesaw )
Price wise, it will probably end up costing the same, altho US Prices are probably cheaper then canadian.
