Usually... buying proven technology, and marketing lead lists is still a gamble. However, the other YC posters are correct in the "never make what you can buy" advice... if and only if there is still mileage in the product life-cycle.

In general, there are a lot of serious rules around energy and fuel industries. Rockwell and Kongsberg technology still dominate for some very practical reasons. Seeing a few small firms fail hard in the area, I would still call it a fools errand for those looking at low hanging fruit. =3