The "iron" stands you want to stay away from are the thin walled square tube cheapies. 2 things, one - wrought iron hasn't actually been iron for at least a century. It dropped out of sight with the blacksmithing trade because iron is hard on machines and is tragically difficult to weld because it isn't homogeneous and heats and cools at different rates causing cracking. This info has no bearing on the performance of a stand, just interesting info. Second bit of info - the thin walled square tube frames, although they will support the weight of your tank, will fall victim to corrosion more quickly than a solid bar would. Also, if you get a chance to look at them closely, the quality of the welds that hold them together tend to be questionable at best. Bad welds are porous as hell which traps moisture from the air inside the welds which several years down the road can lead to spontaneous failure of the weld.
Primary indicator in any case is the "you get what you paid for" rule. If you have the option of buying several iron stands for your tank ranging from $50 to $250, then logic tells you that a few corners were cut in the production of the $50.
