A Mec loader will last a lifetime and will come with everything you need except for charge bar and powder bushings. Charge bars are purchased for the amount of shot they throw, powder bushings are bought separately for the amount of powder they throw and drop into the powder bushing holder in the bar.
If you use the powder bushings a scale isn't needed to load shotgun shells, if you buy an optional adjustable bar the scale is necessary. Use the chart for the powder you select and the appropriate charge bushing. An adjustable charge bar runs about $40 while fixed bars run around $13 each. For my shooting I only load 1-1/8 oz of shot for trap, dove and quail and have an 1-1/4 oz for pheasant loads that I haven't used in years since moving to AZ where there are no wild pheasants to hunt.
The main thing to remember in shotgun loading is that your follow the load manual exactly, no start loads, no working up, no load development. Its not necessary and experimenting can be down right dangerous. You need to match hull type, type of shot, amount of shot, and wad exactly as the data states.
Educate yourself a bit on the types of empty hulls. Read the information about them in the data. You can find shotgun data on both
Alliants website and
Hodgdon's website. High brass or low brass makes no difference to the hull type for example, its the way the case is made, its material and its volume. You can load a 1-5/8 oz 2-3/4" mag load in a low brass case that was originally a trap load with no resulting problems or danger except for a surprise if it gets mixed in with a bunch of trap loads.