Welcome to the forum and thanks for asking our advice.
rfwobbly is right. Your experience loading on the RockChucker will do two things, both very good for you.
1) You will learn the loading steps, how to adjust your dies, what loads to use (what your gun likes, or not), etc
2) You will learn something about the quantities you will want.
In the meantime, we know nothing of your current shooting habits, nor your goals.
We could target our advice better is you shared some information about yourself: (What I use has no relevance to you if our needs are not similar.)
What calibers will you be reloading?
What quantities will you be reloading for those calibers?
How much time will you be willing to devote to those quantities
What is your budget?
Will you be putting your gear away after each session or leave it set up permanently?
How much space will you devote permanently to a loading area, if any?
Do you want it to be portable?
What are your shooting goals? Cheap ammo? Ultimate long-range accuracy? Casual plinking, Serious competition - what kind? Cowboy Action Shooting? Strictly hunting?
In the meantime, every serious, long-time loader I know has a single stage press (and a large number of those are RockChuckers, a fine, venerable and very strong press). Conversion kits, however, are not so good. If you want a progressive (capable of 500-700 rounds per hour), get a Dillon 650 with all the accessories for $1,000 or Hornady L'n'L AP for a little bit less. If your needs will be satisfied with 300-500 rounds per hour, a Dillon 550 or Square Deal for half that. If you only need 200 rounds per hour, you can't beat a Lee Classic Turret, or for 75-150 rounds per hour, any other turret press. (All production estimates are estimates based on others' reported experiences and my experience with single stage and turret presses).
Note: If you will load for more than one caliber, turret presses are easier to swap calibers that progressives, so if small runs of multiple calibers are your style a turret's the thing. If long runs are your thing, the time involved in caliber swaps is less important.
Lost Sheep