Canadian investors looking for exposure to the booming alternative energy sector have a handful of domestic players to choose from, but the local pickings are pretty slim and most of the companies are small. So why not look overseas, to one of the green behemoths that has sprung up on the international scene? ...The fast-growing U.S. wind power industry, driven by favourable government tax policy, is Vestas' largest current market. ...Some analysts are also urging caution over Vestas' high price. "We find the shares are fundamentally overvalued," said analyst Christian Nagstrup of Jyske Bank, a Danish financial institution. The biggest risk he sees at Vestas is a bottleneck in getting parts to build the turbines. Subcontractors have been slow in delivering key components, and that could slow delivery of complete turbines, Mr. Nagstrup said in a recent report.