I reload alot of shells, about 20,000 - 30,000 / year. As far as equipment goes, I recommend buying the fastest and most reliable you can afford.
There are three main shot shell reloading equipment manufacturers in the USA. They are: MEC, Hornady, and Posness-Warren. These are listed in ascending order of cost and quality.
MEC makes the most complete line of loaders. Posness is high end only and Hornady currently lists only 2 models, the DL-366 and the APEX-91.
I have loaded with a DL-366, and APEX-91 automatic, and a MEC-650. I really like the DL-366 and the APEX, I dislike the MEC but I only used it for 28 ga. and the volumes were low.
The Posness loaders start in price around $300.00 and go to > $800.00. There is no doubt that they are the finest loaders made but I have adjusted them for some of my mechanically challenged friends and the Hornady's are alot more user friendly.
The MEC loaders are all stamped sheet metal and in my opinion are not constructed with as much integrity as the Hornady or the Posness. They do offer a wide selection (~$80.00 to $400.00). My particular dislike with the 650 ($150.00) I have is that the shot drop tube is poorly designed and the shot will wedge in the tube at a diameter reduction area. The 12 gauge loaders will not have this problem. The physical force require to load with the 650 is approximately 3X as high as the Hornady.
Ask yourself this when selecting that loader: Including purchasing 500 once fired hulls at $.04 each, loading 3000 shells will cost around $400.00. In only 5 years, the cost of a good loader compared to a cheap loader will be completely masked by the cost of the components. Do I want to put up with a cheap loader?
The quality of the shells produced is not an issue. All the loaders will do approximately the same job. I have loaded many, many rounds with an old DL-105 that I bought used for $35.00 and you couldn't tell a shell loaded with that loader from one loaded with the DL-366.
Since I got the APEX-91, I have relagated the 366 to 28 ga. I have loaded about 4500 shells so far on the APEX and I am very impressed:
The handle force is extremely low.
It was very easy to set up.
It holds enough shot and powder to do 250 shells.
It allows the user to remove shells at any station and automatically
drops primers/shot/powder only when necessary.
I had a missdrilled powder bushing carrier when I got the loader and one
phone call to Hornady had a new one at my door in 3 days.
I whole heartedly recommend the APEX-91.