Yes, but most of those other substances are not
useful, or no more
 useful that the normal mix of isotopes found in nature. B10 is (or
 was, I think they use something else these days), even if it is a one
 trick pony. 
 I wonder what the price of a microgram of U235 is currently? 
 
 I have some uranium-bearing rocks. There's bound to be a gram or two in
 there.