Garmin shares have crossed $300 for the first time, setting a new all-time high after one of the sharpest rallies in the company’s recent history. It is quite a turnaround for a stock that was trading below $190 less than nine months ago. The company is now worth nearly $57 billion. GRMN reached an intraday high of $304 on July 29 before ending the week at $293.78. Even after pulling back slightly, the company is up around 20% over the past five…