The only thing you have to pony out is for the conversion kit. The rest, you can use with each set of dies, if you want to take the time to switch them out.
That being said, with each caliber, you will also need to buy a "die holder" to hold all the dies (I know that is not the correct name, but I am having a brain fade at the moment). Otherwise, you will have to remove all the dies, and reset new ones. Those run about $15 each.
Concerning the powder measure, low powder alarm etc. That you only need to buy one and switch as needed.
Personally, I do not have a low powder indicator, since I can visually check as I go, I just don't see the need for one.
However, a low primer alarm has been very useful, and I would recommend it.
You can buy a powder measure for each setup, but that runs about $79 each. I personally have 3. Two for the loads I do all the time, .45LC for cowboy action, and the other is for my .45ACP.
The last measure I use for the rest of my reloading.
In the end, you can spend $200 per caliber for the measure, conversion kit, the dies, etc. Sounds like a lot, but if you reload a lot, the savings on time makes it worth while.