Remember that even if you design and find all the materials for a Force 6 Power Focus and manage to create it yourself, you're still looking at 48 karma to bond the sucker. It's still a good deal considering how much such a powerful focus helps, but when you consider that most magicians will have wanted to initiate at least once and pick up a spell or two before then, and it's likely that by the time you have the karma or resources to get one, you'll also have the connections (provided you really work at it, of course).