Nothing wrong with inital purchases at higher levels. However, if you believe in the story, averaging down could a good idea (some think its throwing good money after bad, it it depends on the stock/company).
I nibble in and nibble out just incase this situaiton happens. I first bought at $20, and sold those for a paper loss when share prices got to my much lower avg cost.
More times than not, averaging down and trading out of the higher shares has worked for me.