You may be better off buying a Mac Pro, new if money is no object, or older used one if it is.
I have an old Mac Pro 1,1 (2006) with dual Quad core Xeons @ 2.66ghz and its easily the fastest machine I ever had, and I had a few.
The later Mac Pro's have dual 6 core Xeons, but you need a lottery win first
edit: stay away from the 1,1 and 2,1 machines as the boot system (EFI) is 32 bit and they are not able to run the latest OSX. You are not limited to Mac operating system tho, Windoze or Linux work fine with these great machines
I have an old Mac Pro 1,1 (2006) with dual Quad core Xeons @ 2.66ghz and its easily the fastest machine I ever had, and I had a few.
The later Mac Pro's have dual 6 core Xeons, but you need a lottery win first
edit: stay away from the 1,1 and 2,1 machines as the boot system (EFI) is 32 bit and they are not able to run the latest OSX. You are not limited to Mac operating system tho, Windoze or Linux work fine with these great machines