Stainless Steel is a popular choice for grills and smokers. Two types of stainless are used in the manufacture of BBQ cookers: Austenitic and ferritic.
Because it contains more nickel and less steel in the alloy, the most common type of austenitic steel, called 304, is higher quality and higher cost. The most common ferritic steel, called 430, is not as durable and it is harder to weld properly. 430 contains more steel and magnets stick to it. 304 will not attract magnets.
The most significant problem with cheap grills is they often use very thin 430 stainless. These lightweight machines are pretty and shiny on the showroom floor but vulnerable to the demands of grilling. They can quickly develop minute stress fractures that lead to corrosion and reduced performance. They also lose their shine quickly. The image to the right is a 304 stainless steel Bull Grill.
430 is not as durable as 304 and it is harder to weld properly, meaning the weld often rusts or cracks. Very few low-end grills are welded. Almost all are bent and screwed.